diff --git a/internal/api/router.go b/internal/api/router.go
index ba7ed5975..f9d739c96 100644
--- a/internal/api/router.go
+++ b/internal/api/router.go
@@ -3836,6 +3836,15 @@ func (r *Router) reloadSystemSettings() {
 	}
 }
 
+// ReloadSystemSettings re-applies persisted system settings to the router
+// and all notification managers. This must be called after a monitor reload
+// (which recreates the notification manager) to restore instance-wide
+// settings like the webhook private CIDR allowlist that live inside the
+// notification manager's runtime state.
+func (r *Router) ReloadSystemSettings() {
+	r.reloadSystemSettings()
+}
+
 // ServeHTTP implements http.Handler
 func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	// Prevent path traversal attacks
diff --git a/internal/api/router_webhook_cidr_reload_test.go b/internal/api/router_webhook_cidr_reload_test.go
new file mode 100644
index 000000000..396547810
--- /dev/null
+++ b/internal/api/router_webhook_cidr_reload_test.go
@@ -0,0 +1,95 @@
+package api
+
+import (
+	"testing"
+
+	"github.com/rcourtman/pulse-go-rewrite/internal/config"
+	"github.com/rcourtman/pulse-go-rewrite/internal/monitoring"
+)
+
+// TestReloadSystemSettings_AppliesWebhookCIDRsToNewMonitor verifies the fix
+// for issue #1507: after a monitor reload (which recreates the notification
+// manager), ReloadSystemSettings must re-apply the persisted webhook private
+// CIDR allowlist to the new notification manager. Without this, webhooks to
+// private IPs fail after any auto-registration-triggered monitor reload.
+func TestReloadSystemSettings_AppliesWebhookCIDRsToNewMonitor(t *testing.T) {
+	tempDir := t.TempDir()
+
+	persistence := config.NewConfigPersistence(tempDir)
+
+	// Persist system settings with a webhook CIDR allowlist.
+	settings := config.DefaultSystemSettings()
+	settings.WebhookAllowedPrivateCIDRs = "192.168.1.0/24,10.0.0.0/8"
+	if err := persistence.SaveSystemSettings(*settings); err != nil {
+		t.Fatalf("SaveSystemSettings: %v", err)
+	}
+
+	cfg := &config.Config{
+		DataPath:   tempDir,
+		ConfigPath: tempDir,
+	}
+
+	// Create the first monitor — simulates the initial monitor.
+	monitor1, err := monitoring.New(cfg)
+	if err != nil {
+		t.Fatalf("monitoring.New (initial): %v", err)
+	}
+	t.Cleanup(func() { monitor1.Stop() })
+
+	// Create a minimal Router with the persistence and monitor set.
+	// reloadSystemSettings only reads r.persistence, r.monitor, r.mtMonitor,
+	// and r.config — the other fields are nil-safe.
+	router := &Router{
+		config:      cfg,
+		persistence: persistence,
+		monitor:     monitor1,
+	}
+
+	// First call applies CIDRs to the initial monitor.
+	router.ReloadSystemSettings()
+
+	nm1 := monitor1.GetNotificationManager()
+	if nm1 == nil {
+		t.Fatal("initial monitor has no notification manager")
+	}
+	if err := nm1.ValidateWebhookURL("http://192.168.1.50/hook"); err != nil {
+		t.Fatalf("initial monitor: expected CIDR to allow 192.168.1.50, got: %v", err)
+	}
+
+	// Simulate a monitor reload: create a fresh monitor with a brand-new
+	// notification manager (empty CIDR allowlist).
+	monitor2, err := monitoring.New(cfg)
+	if err != nil {
+		t.Fatalf("monitoring.New (reload): %v", err)
+	}
+	t.Cleanup(func() { monitor2.Stop() })
+
+	// Before the fix: the reload path in server.go never called
+	// ReloadSystemSettings, so the new notification manager would have
+	// an empty allowlist and reject private IPs.
+	nm2 := monitor2.GetNotificationManager()
+	if nm2 == nil {
+		t.Fatal("reloaded monitor has no notification manager")
+	}
+	if err := nm2.ValidateWebhookURL("http://192.168.1.50/hook"); err == nil {
+		t.Fatal("fresh notification manager should reject private IP before settings are re-applied")
+	}
+
+	// Now update the router's monitor reference (as SetMonitor does during reload).
+	router.monitor = monitor2
+
+	// Call ReloadSystemSettings — this is the fix.
+	router.ReloadSystemSettings()
+
+	// The new notification manager should now have the persisted CIDR allowlist.
+	if err := nm2.ValidateWebhookURL("http://192.168.1.50/hook"); err != nil {
+		t.Fatalf("after ReloadSystemSettings: expected CIDR to allow 192.168.1.50, got: %v", err)
+	}
+	if err := nm2.ValidateWebhookURL("http://10.5.5.5/hook"); err != nil {
+		t.Fatalf("after ReloadSystemSettings: expected CIDR to allow 10.5.5.5, got: %v", err)
+	}
+	// IPs outside the allowlist should still be rejected.
+	if err := nm2.ValidateWebhookURL("http://172.16.0.1/hook"); err == nil {
+		t.Fatal("after ReloadSystemSettings: expected 172.16.0.1 to be rejected (not in allowlist)")
+	}
+}
diff --git a/pkg/server/server.go b/pkg/server/server.go
index ef3e6dc7a..45bc563d0 100644
--- a/pkg/server/server.go
+++ b/pkg/server/server.go
@@ -409,6 +409,11 @@ func Run(ctx context.Context, version string) error {
 			if cfg := reloadableMonitor.GetConfig(); cfg != nil {
 				router.SetConfig(cfg)
 			}
+			// Re-apply system settings (e.g. webhook private CIDR allowlist)
+			// to the freshly recreated notification manager. Without this,
+			// instance-wide settings stored inside the notification manager
+			// are lost on every monitor reload triggered by auto-registration.
+			router.ReloadSystemSettings()
 		}
 		return nil
 	}