diff --git a/src/Backend/AutopilotMonitor.Functions.Tests/GetTpmPssUnsupportedFunctionTests.cs b/src/Backend/AutopilotMonitor.Functions.Tests/GetTpmPssUnsupportedFunctionTests.cs
new file mode 100644
index 00000000..a2d73884
--- /dev/null
+++ b/src/Backend/AutopilotMonitor.Functions.Tests/GetTpmPssUnsupportedFunctionTests.cs
@@ -0,0 +1,194 @@
+using AutopilotMonitor.Functions.Functions.Reports;
+using AutopilotMonitor.Shared.DataAccess;
+
+namespace AutopilotMonitor.Functions.Tests;
+
+/// <summary>
+/// Tests for the TPM-PSS-unsupported aggregation logic extracted from
+/// GetTpmPssUnsupportedFunction. All tests target the pure static BuildAggregatedResult
+/// method — no HTTP or DI needed. Aggregation is by serial number (the TPM incompatibility
+/// is a per-device condition, not a per-model one — firmware levels differ within a model).
+/// </summary>
+public class GetTpmPssUnsupportedFunctionTests
+{
+    private static readonly DateTime T0 = new(2026, 3, 1, 12, 0, 0, DateTimeKind.Utc);
+
+    // =========================================================================
+    // Empty / no matching reports
+    // =========================================================================
+
+    [Fact]
+    public void BuildAggregatedResult_EmptyList_ReturnsEmpty()
+    {
+        var (aggregated, totalRawReports) = GetTpmPssUnsupportedFunction.BuildAggregatedResult([]);
+
+        Assert.Empty(aggregated);
+        Assert.Equal(0, totalRawReports);
+    }
+
+    [Fact]
+    public void BuildAggregatedResult_FiltersTpmPssUnsupportedOnly()
+    {
+        var reports = new List<DistressReportEntry>
+        {
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN1", T0),
+            MakeEntry("DeviceNotRegistered", "Lenovo", "ThinkPad T14", "SN2", T0.AddMinutes(1)),
+            MakeEntry("AuthCertificateRejected", "HP", "EliteBook", "SN3", T0.AddMinutes(2)),
+        };
+
+        var (aggregated, totalRawReports) = GetTpmPssUnsupportedFunction.BuildAggregatedResult(reports);
+
+        Assert.Single(aggregated);
+        Assert.Equal(1, totalRawReports);
+    }
+
+    // =========================================================================
+    // Aggregation by serial number
+    // =========================================================================
+
+    [Fact]
+    public void BuildAggregatedResult_AggregatesBySerialCaseInsensitive()
+    {
+        var reports = new List<DistressReportEntry>
+        {
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "S4SQ8685", T0),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "s4sq8685", T0.AddMinutes(1)),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", " S4SQ8685 ", T0.AddMinutes(2)),
+        };
+
+        var (aggregated, totalRawReports) = GetTpmPssUnsupportedFunction.BuildAggregatedResult(reports);
+
+        Assert.Single(aggregated);
+        Assert.Equal(3, totalRawReports);
+        var item = ToDynamic(aggregated[0]);
+        Assert.Equal(3, (int)item.attemptCount);
+    }
+
+    [Fact]
+    public void BuildAggregatedResult_DistinctSerials_ProduceDistinctRows()
+    {
+        var reports = new List<DistressReportEntry>
+        {
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN1", T0),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN2", T0.AddMinutes(1)),
+            MakeEntry("TpmPssUnsupported", "Microsoft", "Surface Book", "SN3", T0.AddMinutes(2)),
+        };
+
+        var (aggregated, totalRawReports) = GetTpmPssUnsupportedFunction.BuildAggregatedResult(reports);
+
+        Assert.Equal(3, aggregated.Count);
+        Assert.Equal(3, totalRawReports);
+    }
+
+    [Fact]
+    public void BuildAggregatedResult_UsesMostRecentManufacturerModel()
+    {
+        var reports = new List<DistressReportEntry>
+        {
+            MakeEntry("TpmPssUnsupported", "OldMfr", "OldModel", "SN1", T0),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN1", T0.AddMinutes(5)),
+        };
+
+        var (aggregated, _) = GetTpmPssUnsupportedFunction.BuildAggregatedResult(reports);
+
+        var item = ToDynamic(aggregated[0]);
+        Assert.Equal("Lenovo", (string)item.manufacturer);
+        Assert.Equal("ThinkCentre M720q", (string)item.model);
+        Assert.Equal("SN1", (string)item.serialNumber);
+    }
+
+    // =========================================================================
+    // Timestamps
+    // =========================================================================
+
+    [Fact]
+    public void BuildAggregatedResult_FirstSeenLastSeen_Correct()
+    {
+        var t1 = T0;
+        var t2 = T0.AddHours(1);
+        var t3 = T0.AddHours(2);
+
+        var reports = new List<DistressReportEntry>
+        {
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN1", t2),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN1", t1),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN1", t3),
+        };
+
+        var (aggregated, _) = GetTpmPssUnsupportedFunction.BuildAggregatedResult(reports);
+
+        var item = ToDynamic(aggregated[0]);
+        Assert.Equal(t1, (DateTime)item.firstSeen);
+        Assert.Equal(t3, (DateTime)item.lastSeen);
+    }
+
+    [Fact]
+    public void BuildAggregatedResult_OrderedByLastSeenDescending()
+    {
+        var reports = new List<DistressReportEntry>
+        {
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "SN1", T0),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkPad X13", "SN2", T0.AddHours(2)),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720s", "SN3", T0.AddHours(1)),
+        };
+
+        var (aggregated, _) = GetTpmPssUnsupportedFunction.BuildAggregatedResult(reports);
+
+        Assert.Equal(3, aggregated.Count);
+        var first = ToDynamic(aggregated[0]);
+        var second = ToDynamic(aggregated[1]);
+        var third = ToDynamic(aggregated[2]);
+
+        Assert.True((DateTime)first.lastSeen > (DateTime)second.lastSeen);
+        Assert.True((DateTime)second.lastSeen > (DateTime)third.lastSeen);
+    }
+
+    // =========================================================================
+    // Null / empty serial number
+    // =========================================================================
+
+    [Fact]
+    public void BuildAggregatedResult_NullOrEmptySerials_GroupedIntoSingleBucket()
+    {
+        var reports = new List<DistressReportEntry>
+        {
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", null, T0),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "", T0.AddMinutes(1)),
+            MakeEntry("TpmPssUnsupported", "Lenovo", "ThinkCentre M720q", "   ", T0.AddMinutes(2)),
+        };
+
+        var (aggregated, _) = GetTpmPssUnsupportedFunction.BuildAggregatedResult(reports);
+
+        Assert.Single(aggregated);
+        var item = ToDynamic(aggregated[0]);
+        Assert.Equal(3, (int)item.attemptCount);
+    }
+
+    // =========================================================================
+    // Helpers
+    // =========================================================================
+
+    private static DistressReportEntry MakeEntry(
+        string errorType, string? manufacturer, string? model, string? serial, DateTime ingestedAt) =>
+        new()
+        {
+            TenantId = "test-tenant",
+            ErrorType = errorType,
+            Manufacturer = manufacturer,
+            Model = model,
+            SerialNumber = serial,
+            IngestedAt = ingestedAt,
+            AgentTimestamp = ingestedAt,
+        };
+
+    private static dynamic ToDynamic(object obj)
+    {
+        var type = obj.GetType();
+        var dict = new System.Dynamic.ExpandoObject() as IDictionary<string, object?>;
+        foreach (var prop in type.GetProperties())
+        {
+            dict[prop.Name] = prop.GetValue(obj);
+        }
+        return dict;
+    }
+}
diff --git a/src/Backend/AutopilotMonitor.Functions.Tests/HardwareRejectionNotificationTrackerKeyTests.cs b/src/Backend/AutopilotMonitor.Functions.Tests/HardwareRejectionNotificationTrackerKeyTests.cs
index 944b7b5d..6976915b 100644
--- a/src/Backend/AutopilotMonitor.Functions.Tests/HardwareRejectionNotificationTrackerKeyTests.cs
+++ b/src/Backend/AutopilotMonitor.Functions.Tests/HardwareRejectionNotificationTrackerKeyTests.cs
@@ -59,4 +59,35 @@ public class HardwareRejectionNotificationTrackerKeyTests
         var key = TableHardwareRejectionNotificationTracker.BuildRowKey("", "");
         Assert.Equal("|", key);
     }
+
+    // =========================================================================
+    // TPM PSS row keys (same table, "tpmpss|" prefix — dedup per serial)
+    // =========================================================================
+
+    [Fact]
+    public void BuildTpmPssRowKey_LowercasesTrimsAndPrefixes()
+    {
+        var key = TableHardwareRejectionNotificationTracker.BuildTpmPssRowKey("  S4SQ8685 ");
+        Assert.Equal("tpmpss|s4sq8685", key);
+    }
+
+    [Theory]
+    [InlineData("S4SQ8685", "s4sq8685")]
+    [InlineData("s4Sq8685", "S4SQ8685")]
+    public void BuildTpmPssRowKey_IsCaseInsensitive(string serialA, string serialB)
+    {
+        Assert.Equal(
+            TableHardwareRejectionNotificationTracker.BuildTpmPssRowKey(serialA),
+            TableHardwareRejectionNotificationTracker.BuildTpmPssRowKey(serialB));
+    }
+
+    [Fact]
+    public void BuildTpmPssRowKey_DoesNotCollideWithHardwareKeyOfSameText()
+    {
+        // A hardware key is "{mfr}|{model}"; the TPM key's fixed "tpmpss|" prefix keeps the
+        // two key spaces disjoint within the shared table.
+        var hardwareKey = TableHardwareRejectionNotificationTracker.BuildRowKey("Lenovo", "S4SQ8685");
+        var tpmKey = TableHardwareRejectionNotificationTracker.BuildTpmPssRowKey("S4SQ8685");
+        Assert.NotEqual(hardwareKey, tpmKey);
+    }
 }
diff --git a/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs b/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs
index d0495270..25bdbeb6 100644
--- a/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs
+++ b/src/Backend/AutopilotMonitor.Functions.Tests/TenantNotificationAudienceCatalogTests.cs
@@ -13,6 +13,7 @@ public class TenantNotificationAudienceCatalogTests
 {
     [Theory]
     [InlineData("hardware_rejection", NotificationAudience.Admin)]
+    [InlineData("tpm_pss_unsupported", NotificationAudience.Admin)]
     [InlineData("sla_breach", NotificationAudience.Member)]
     [InlineData("sla_consecutive_failures", NotificationAudience.Member)]
     [InlineData("sla_resolved", NotificationAudience.Member)]
diff --git a/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs b/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs
index ce535d7a..643e9d2a 100644
--- a/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs
+++ b/src/Backend/AutopilotMonitor.Functions/DataAccess/TableStorage/TableHardwareRejectionNotificationTracker.cs
@@ -9,7 +9,10 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
 {
     /// <summary>
     /// Table Storage implementation of <see cref="IHardwareRejectionNotificationTracker"/>.
-    /// PartitionKey = tenantId (lowercased), RowKey = "{manufacturer-lower}|{model-lower}" (trimmed).
+    /// PartitionKey = tenantId (lowercased). RowKey encodes the dedup subject:
+    ///   - hardware rejection: "{manufacturer-lower}|{model-lower}" (trimmed)
+    ///   - TPM PSS unsupported: "tpmpss|{serial-lower}" (trimmed; the literal "tpmpss" prefix
+    ///     cannot collide with a hardware key because no real manufacturer is named "tpmpss")
     /// Race-safe via AddEntityAsync: Azure Table Storage returns 409 Conflict if the entity already exists.
     /// </summary>
     public class TableHardwareRejectionNotificationTracker : IHardwareRejectionNotificationTracker
@@ -68,6 +71,44 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
             }
         }
 
+        public async Task<bool> TryRegisterFirstTpmPssNotificationAsync(string tenantId, string serialNumber)
+        {
+            if (string.IsNullOrWhiteSpace(tenantId) || string.IsNullOrWhiteSpace(serialNumber))
+                return false;
+
+            var partitionKey = tenantId.ToLowerInvariant();
+            var rowKey = BuildTpmPssRowKey(serialNumber);
+
+            var entity = new TableEntity(partitionKey, rowKey)
+            {
+                ["TenantId"] = tenantId,
+                ["SerialNumber"] = serialNumber,
+                ["FirstNotifiedAt"] = DateTime.UtcNow
+            };
+
+            try
+            {
+                await _table.AddEntityAsync(entity);
+                _logger.LogInformation(
+                    "TpmPssUnsupported tracker registered: tenant={TenantId} sn={SerialNumber}",
+                    tenantId, serialNumber);
+                return true;
+            }
+            catch (RequestFailedException ex) when (ex.Status == 409)
+            {
+                // Already notified for this (tenant, serial) — no second bell.
+                return false;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex,
+                    "TpmPssUnsupported tracker failed: tenant={TenantId} sn={SerialNumber}",
+                    tenantId, serialNumber);
+                // On unexpected failure, return false so we do not double-fire if the row was actually written.
+                return false;
+            }
+        }
+
         public async Task<int> DeleteOlderThanAsync(DateTime cutoffUtc)
         {
             try
@@ -111,5 +152,11 @@ namespace AutopilotMonitor.Functions.DataAccess.TableStorage
             var mdl = (model ?? string.Empty).Trim().ToLowerInvariant();
             return $"{mfr}|{mdl}";
         }
+
+        internal static string BuildTpmPssRowKey(string serialNumber)
+        {
+            var sn = (serialNumber ?? string.Empty).Trim().ToLowerInvariant();
+            return $"tpmpss|{sn}";
+        }
     }
 }
diff --git a/src/Backend/AutopilotMonitor.Functions/Functions/Ingest/ReportDistressFunction.cs b/src/Backend/AutopilotMonitor.Functions/Functions/Ingest/ReportDistressFunction.cs
index cb560417..f77c64d8 100644
--- a/src/Backend/AutopilotMonitor.Functions/Functions/Ingest/ReportDistressFunction.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Functions/Ingest/ReportDistressFunction.cs
@@ -269,6 +269,36 @@ namespace AutopilotMonitor.Functions.Functions.Ingest
                     }
                 }
 
+                // In-app bell notification on first-ever TPM-PSS incompatibility per (tenant, serial).
+                // Same lifetime-dedup pattern as the hardware-rejection bell above. No webhook —
+                // volume is tiny and the remediation (TPM firmware update / device replacement)
+                // is not time-critical. Reports without a serial number cannot be deduped and
+                // fire no bell; they still appear in the tenant insights panel.
+                if (report.ErrorType == DistressErrorType.TpmPssUnsupported
+                    && !string.IsNullOrEmpty(serialNumber))
+                {
+                    try
+                    {
+                        var isFirst = await _hardwareBellTracker
+                            .TryRegisterFirstTpmPssNotificationAsync(tenantId, serialNumber);
+                        if (isFirst)
+                        {
+                            var deviceLabel = string.Join(" ",
+                                new[] { manufacturer, model }.Where(s => !string.IsNullOrEmpty(s)));
+                            await _tenantNotificationService.CreateNotificationAsync(
+                                tenantId,
+                                type: "tpm_pss_unsupported",
+                                title: "Device with incompatible TPM detected",
+                                message: $"Device {serialNumber}{(deviceLabel.Length > 0 ? $" ({deviceLabel})" : "")} reported a TPM that cannot perform RSA-PSS signing — the agent on this device cannot authenticate. A TPM firmware update or device replacement is required.",
+                                href: "/settings/tenant/hardware-whitelist");
+                        }
+                    }
+                    catch (Exception bellEx)
+                    {
+                        _logger.LogWarning(bellEx, "TpmPssUnsupported bell notification failed for tenant {TenantId}", tenantId);
+                    }
+                }
+
                 // Structured log (Warning, not Critical — data is unverified)
                 _logger.LogWarning(
                     "AgentDistress [{ErrorType}] tenant={TenantId} mfr={Manufacturer} model={Model} sn={SerialNumber} http={HttpStatusCode} ver={AgentVersion} certState={CertSourceState} thumbprint={CertThumbprint}: {Message}",
diff --git a/src/Backend/AutopilotMonitor.Functions/Functions/Reports/GetTpmPssUnsupportedFunction.cs b/src/Backend/AutopilotMonitor.Functions/Functions/Reports/GetTpmPssUnsupportedFunction.cs
new file mode 100644
index 00000000..11c0254a
--- /dev/null
+++ b/src/Backend/AutopilotMonitor.Functions/Functions/Reports/GetTpmPssUnsupportedFunction.cs
@@ -0,0 +1,95 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using AutopilotMonitor.Functions.Helpers;
+using AutopilotMonitor.Shared.DataAccess;
+using Microsoft.Azure.Functions.Worker;
+using Microsoft.Azure.Functions.Worker.Http;
+using Microsoft.Extensions.Logging;
+
+namespace AutopilotMonitor.Functions.Functions.Reports
+{
+    /// <summary>
+    /// Tenant-scoped endpoint: returns devices whose TPM-backed client certificate cannot
+    /// perform RSA-PSS signing (Schannel silently drops the cert from TLS client-auth on
+    /// Windows 11 25H2+, so the agent can never authenticate), aggregated by serial number.
+    /// Data comes from distress reports with ErrorType == "TpmPssUnsupported".
+    ///
+    /// Informational only — the remediation is a TPM firmware update or device replacement,
+    /// not a portal action. The 14-day horizon is enforced by the distress-report retention
+    /// cleanup, not by this function.
+    /// Authentication + MemberRead authorization enforced by PolicyEnforcementMiddleware.
+    /// </summary>
+    public class GetTpmPssUnsupportedFunction
+    {
+        private readonly ILogger<GetTpmPssUnsupportedFunction> _logger;
+        private readonly IDistressReportRepository _repository;
+
+        public GetTpmPssUnsupportedFunction(
+            ILogger<GetTpmPssUnsupportedFunction> logger,
+            IDistressReportRepository repository)
+        {
+            _logger = logger;
+            _repository = repository;
+        }
+
+        [Function("GetTpmPssUnsupported")]
+        public async Task<HttpResponseData> Run(
+            [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "audit/tpm-pss-unsupported")] HttpRequestData req)
+        {
+            try
+            {
+                string tenantId = TenantHelper.GetTenantId(req);
+
+                var reports = await _repository.GetDistressReportsAsync(tenantId, maxResults: 200);
+                var (aggregated, totalRawReports) = BuildAggregatedResult(reports);
+
+                return await req.OkAsync(new
+                {
+                    success = true,
+                    aggregated,
+                    totalRawReports,
+                    dataQualityNotice = "This data is from pre-authentication distress reports and is UNVERIFIED. Devices reported here have a TPM that cannot perform RSA-PSS signing, so their agent cannot authenticate to the backend. Serial number, manufacturer, and model values are self-reported by devices."
+                });
+            }
+            catch (Exception ex)
+            {
+                return await req.InternalServerErrorAsync(_logger, ex, "Get TPM PSS unsupported devices");
+            }
+        }
+
+        /// <summary>
+        /// Filters distress reports to TpmPssUnsupported and aggregates by serial number.
+        /// Reports with no serial number are grouped into a single "unknown serial" bucket.
+        /// Extracted as public static for testability.
+        /// </summary>
+        public static (List<object> aggregated, int totalRawReports) BuildAggregatedResult(
+            List<DistressReportEntry> reports)
+        {
+            var tpmReports = reports
+                .Where(r => string.Equals(r.ErrorType, "TpmPssUnsupported", StringComparison.OrdinalIgnoreCase))
+                .ToList();
+
+            var aggregated = tpmReports
+                .GroupBy(r => (r.SerialNumber ?? "").Trim().ToLowerInvariant())
+                .Select(g =>
+                {
+                    var mostRecent = g.OrderByDescending(r => r.IngestedAt).First();
+
+                    return new
+                    {
+                        serialNumber = mostRecent.SerialNumber ?? "",
+                        manufacturer = mostRecent.Manufacturer ?? "",
+                        model = mostRecent.Model ?? "",
+                        attemptCount = g.Count(),
+                        firstSeen = g.Min(r => r.IngestedAt),
+                        lastSeen = g.Max(r => r.IngestedAt)
+                    };
+                })
+                .OrderByDescending(a => a.lastSeen)
+                .ToList<object>();
+
+            return (aggregated, tpmReports.Count);
+        }
+    }
+}
diff --git a/src/Backend/AutopilotMonitor.Functions/Security/EndpointAccessPolicyCatalog.cs b/src/Backend/AutopilotMonitor.Functions/Security/EndpointAccessPolicyCatalog.cs
index 90df5f3c..f5cf97fd 100644
--- a/src/Backend/AutopilotMonitor.Functions/Security/EndpointAccessPolicyCatalog.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Security/EndpointAccessPolicyCatalog.cs
@@ -244,6 +244,7 @@ public static class EndpointAccessPolicyCatalog
         new("GET",    "audit/logs",                EndpointPolicy.MemberRead),
         new("GET",    "audit/hardware-rejected", EndpointPolicy.MemberRead),
         new("GET",    "audit/device-not-registered", EndpointPolicy.MemberRead),
+        new("GET",    "audit/tpm-pss-unsupported", EndpointPolicy.MemberRead),
         new("GET",    "diagnostics/download-url",  EndpointPolicy.MemberRead, TenantScoping.QueryParam),
         new("POST",   "diagnostics/download-ticket", EndpointPolicy.MemberRead, TenantScoping.QueryParam),
         new("GET",    "rules/gather",              EndpointPolicy.MemberRead),
diff --git a/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs b/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs
index e2c262ab..fcb3d45c 100644
--- a/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs
+++ b/src/Backend/AutopilotMonitor.Functions/Services/TenantNotificationAudienceCatalog.cs
@@ -26,6 +26,7 @@ public static class TenantNotificationAudienceCatalog
     private static readonly Dictionary<string, NotificationAudience> _map = new(System.StringComparer.OrdinalIgnoreCase)
     {
         ["hardware_rejection"]       = NotificationAudience.Admin,
+        ["tpm_pss_unsupported"]      = NotificationAudience.Admin,
         ["sla_breach"]               = NotificationAudience.Member,
         ["sla_consecutive_failures"] = NotificationAudience.Member,
         ["sla_resolved"]             = NotificationAudience.Member,
diff --git a/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs b/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs
index d7f3bfc0..104b6a13 100644
--- a/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs
+++ b/src/Shared/AutopilotMonitor.Shared/DataAccess/IHardwareRejectionNotificationTracker.cs
@@ -4,20 +4,30 @@ using System.Threading.Tasks;
 namespace AutopilotMonitor.Shared.DataAccess
 {
     /// <summary>
-    /// Tracks which (tenant, manufacturer, model) combinations have already triggered a bell
-    /// notification. Used by ReportDistressFunction to fire a tenant-admin notification at most
-    /// once per model per tenant (lifetime dedup).
+    /// First-notification dedup store for distress-driven bell notifications. Used by
+    /// ReportDistressFunction to fire each tenant-admin notification at most once per subject
+    /// (lifetime dedup): hardware rejections per (tenant, manufacturer, model) and TPM PSS
+    /// incompatibilities per (tenant, serial number).
     /// </summary>
     public interface IHardwareRejectionNotificationTracker
     {
         /// <summary>
-        /// Atomically records a first-time notification for the given (tenantId, manufacturer, model).
+        /// Atomically records a first-time hardware-rejection notification for the given
+        /// (tenantId, manufacturer, model).
         /// Returns true if this is the first time (caller should fire the notification),
         /// false if an entry already exists (caller should skip).
         /// Manufacturer and model are matched case-insensitively after trim.
         /// </summary>
         Task<bool> TryRegisterFirstNotificationAsync(string tenantId, string manufacturer, string model);
 
+        /// <summary>
+        /// Atomically records a first-time TPM-PSS-unsupported notification for the given
+        /// (tenantId, serialNumber). Same semantics as
+        /// <see cref="TryRegisterFirstNotificationAsync"/>; the serial number is matched
+        /// case-insensitively after trim.
+        /// </summary>
+        Task<bool> TryRegisterFirstTpmPssNotificationAsync(string tenantId, string serialNumber);
+
         /// <summary>
         /// Retention cleanup: deletes tracker rows whose FirstNotifiedAt is older than
         /// <paramref name="cutoffUtc"/>. Pruning re-arms the dedup for that model. Returns rows deleted.
diff --git a/src/Web/autopilot-monitor-web/app/settings/components/TpmIncompatibleDevicesInsights.tsx b/src/Web/autopilot-monitor-web/app/settings/components/TpmIncompatibleDevicesInsights.tsx
new file mode 100644
index 00000000..408417a3
--- /dev/null
+++ b/src/Web/autopilot-monitor-web/app/settings/components/TpmIncompatibleDevicesInsights.tsx
@@ -0,0 +1,146 @@
+"use client";
+
+import { useState, useEffect, useCallback } from "react";
+import { api } from "@/lib/api";
+import { authenticatedFetch } from "@/lib/authenticatedFetch";
+
+interface AggregatedTpmPssUnsupported {
+  serialNumber: string;
+  manufacturer: string;
+  model: string;
+  attemptCount: number;
+  firstSeen: string;
+  lastSeen: string;
+}
+
+interface TpmPssUnsupportedResponse {
+  success: boolean;
+  aggregated: AggregatedTpmPssUnsupported[];
+  totalRawReports: number;
+  dataQualityNotice: string;
+}
+
+interface TpmIncompatibleDevicesInsightsProps {
+  getAccessToken: () => Promise<string | null>;
+}
+
+function formatDate(iso: string): string {
+  try {
+    return new Date(iso).toLocaleString(undefined, {
+      month: "short",
+      day: "numeric",
+      hour: "2-digit",
+      minute: "2-digit",
+    });
+  } catch {
+    return iso;
+  }
+}
+
+/**
+ * Devices whose TPM cannot perform RSA-PSS signing — Schannel silently drops their client
+ * certificate from TLS client-auth (Windows 11 25H2+ prefers PSS), so the agent can never
+ * authenticate. Remediation is a TPM firmware update or device replacement.
+ *
+ * Unlike the sibling insights panels this one renders nothing while loading, on error, and
+ * when no device is affected: it is a rare condition and a third permanent card in the
+ * section would be noise for the common all-clear case.
+ */
+export default function TpmIncompatibleDevicesInsights({
+  getAccessToken,
+}: TpmIncompatibleDevicesInsightsProps) {
+  const [data, setData] = useState<TpmPssUnsupportedResponse | null>(null);
+
+  const fetchData = useCallback(async () => {
+    try {
+      const res = await authenticatedFetch(api.distress.tpmPssUnsupported(), getAccessToken);
+      if (!res.ok) return;
+      const json: TpmPssUnsupportedResponse = await res.json();
+      setData(json);
+    } catch {
+      // Silent degrade — the panel is a secondary insight; the section stays usable without it.
+    }
+  }, [getAccessToken]);
+
+  useEffect(() => {
+    fetchData();
+  }, [fetchData]);
+
+  if (!data || data.aggregated.length === 0) {
+    return null;
+  }
+
+  return (
+    <div className="bg-white rounded-lg shadow mt-6">
+      {/* Header */}
+      <div className="p-6 border-b border-gray-200 bg-gradient-to-r from-amber-50 to-orange-50">
+        <div className="flex items-center justify-between">
+          <div className="flex items-center space-x-2">
+            <svg className="w-6 h-6 text-amber-600" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 9v2m0 4h.01m-6.938 4h13.856c1.54 0 2.502-1.667 1.732-2.5L13.732 4c-.77-.833-1.964-.833-2.732 0L4.082 16.5c-.77.833.192 2.5 1.732 2.5z" />
+            </svg>
+            <div>
+              <h3 className="text-lg font-semibold text-gray-900">
+                Devices with Incompatible TPM
+                <span className="ml-2 text-xs font-normal text-gray-500">Last 14 days</span>
+              </h3>
+              <p className="text-sm text-gray-500 mt-0.5">
+                These devices have a TPM that cannot perform RSA-PSS signing, so the agent cannot
+                authenticate and no enrollment data is reported
+              </p>
+            </div>
+          </div>
+          <span className="inline-flex items-center px-2 py-0.5 rounded text-xs font-medium bg-amber-100 text-amber-800">
+            Unverified
+          </span>
+        </div>
+      </div>
+
+      {/* Explanation + remediation */}
+      <div className="px-6 pt-4 space-y-3">
+        <div className="bg-amber-50 border border-amber-200 rounded-lg p-3">
+          <p className="text-xs text-amber-800">
+            Windows 11 25H2 and later prefer RSA-PSS for TLS client authentication. On these devices
+            the TPM-backed Intune certificate cannot sign with RSA-PSS (common on older TPM firmware),
+            so Windows silently withholds the certificate and every connection attempt is rejected.
+            Remediation: update the TPM firmware via the vendor&apos;s tooling, or replace the device.
+            This data comes from pre-authentication distress signals; serial number, manufacturer,
+            and model values are self-reported and unverified.
+          </p>
+        </div>
+      </div>
+
+      <div className="p-6">
+        <div className="overflow-x-auto">
+          <table className="min-w-full text-sm">
+            <thead>
+              <tr className="text-left text-xs text-gray-500 uppercase tracking-wider border-b border-gray-200">
+                <th className="pb-2 pr-4">Serial Number</th>
+                <th className="pb-2 pr-4">Manufacturer</th>
+                <th className="pb-2 pr-4">Model</th>
+                <th className="pb-2 pr-4 text-right">Attempts</th>
+                <th className="pb-2 pr-4">First Seen</th>
+                <th className="pb-2">Last Seen</th>
+              </tr>
+            </thead>
+            <tbody className="divide-y divide-gray-100">
+              {data.aggregated.map((row, idx) => (
+                <tr key={`${row.serialNumber}|${idx}`}>
+                  <td className="py-3 pr-4 font-mono text-gray-900">{row.serialNumber || "–"}</td>
+                  <td className="py-3 pr-4 text-gray-700">{row.manufacturer || "–"}</td>
+                  <td className="py-3 pr-4 text-gray-700">{row.model || "–"}</td>
+                  <td className="py-3 pr-4 text-right font-mono text-gray-900">{row.attemptCount}</td>
+                  <td className="py-3 pr-4 text-gray-500 whitespace-nowrap">{formatDate(row.firstSeen)}</td>
+                  <td className="py-3 text-gray-500 whitespace-nowrap">{formatDate(row.lastSeen)}</td>
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        </div>
+        <p className="text-xs text-gray-400 mt-3">
+          {data.totalRawReports} total report{data.totalRawReports !== 1 ? "s" : ""} across {data.aggregated.length} device{data.aggregated.length !== 1 ? "s" : ""}
+        </p>
+      </div>
+    </div>
+  );
+}
diff --git a/src/Web/autopilot-monitor-web/app/settings/tenant/sections/SectionHardwareWhitelist.tsx b/src/Web/autopilot-monitor-web/app/settings/tenant/sections/SectionHardwareWhitelist.tsx
index 1af260e3..08bf5d69 100644
--- a/src/Web/autopilot-monitor-web/app/settings/tenant/sections/SectionHardwareWhitelist.tsx
+++ b/src/Web/autopilot-monitor-web/app/settings/tenant/sections/SectionHardwareWhitelist.tsx
@@ -6,6 +6,7 @@ import { useTenantConfig } from "../../TenantConfigContext";
 import { TenantNotifications } from "../../TenantNotifications";
 import HardwareWhitelistSection from "../../components/HardwareWhitelistSection";
 import HardwareRejectionInsights from "../../components/HardwareRejectionInsights";
+import TpmIncompatibleDevicesInsights from "../../components/TpmIncompatibleDevicesInsights";
 
 function parseList(csv: string): string[] {
   return csv.split(",").map((s) => s.trim()).filter(Boolean);
@@ -65,6 +66,7 @@ export function SectionHardwareWhitelist() {
         hasWebhook={hasWebhook}
         readOnly={!canEditConfig}
       />
+      <TpmIncompatibleDevicesInsights getAccessToken={getAccessToken} />
     </>
   );
 }
diff --git a/src/Web/autopilot-monitor-web/lib/api.ts b/src/Web/autopilot-monitor-web/lib/api.ts
index d24acbdd..ee4d4692 100644
--- a/src/Web/autopilot-monitor-web/lib/api.ts
+++ b/src/Web/autopilot-monitor-web/lib/api.ts
@@ -409,6 +409,7 @@ export const api = {
   distress: {
     hardwareRejected: () => `${API_BASE_URL}/api/audit/hardware-rejected`,
     deviceNotRegistered: () => `${API_BASE_URL}/api/audit/device-not-registered`,
+    tpmPssUnsupported: () => `${API_BASE_URL}/api/audit/tpm-pss-unsupported`,
   },
 
   // ── Ops Events ───────────────────────────────────────────────────────────