diff --git a/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteStreamGrpcServerTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteStreamGrpcServerTests.cs
index 81e00fc0..1e3b01c7 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteStreamGrpcServerTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/SiteStreamGrpcServerTests.cs
@@ -386,15 +386,23 @@ public class SiteStreamGrpcServerTests : TestKit
         // While the stream is up the gauge is one above whatever baseline other
         // (possibly parallel) tests left behind — read relative so the assertion
         // is robust to test interleaving on the process-wide static counter.
-        Assert.Equal(baseline + 1, ReadGauge());
+        //
+        // SiteConnectionOpened() runs AFTER the _activeStreams insertion that
+        // WaitForConditionAsync(ActiveStreamCount == 1) keys off (see
+        // SiteStreamGrpcServer.SubscribeInstance), so a one-shot ReadGauge() here
+        // can race the increment under full-suite CPU oversubscription. Poll the
+        // gauge with a generous timeout until it reaches baseline + 1.
+        AwaitAssert(() => Assert.Equal(baseline + 1, ReadGauge()), TimeSpan.FromSeconds(5));
 
         cts.Cancel();
         await streamTask;
         await WaitForConditionAsync(() => server.ActiveStreamCount == 0);
 
         // After the cancel path runs the finally, the gauge is balanced back to
-        // the baseline — no leaked "up" count.
-        Assert.Equal(baseline, ReadGauge());
+        // the baseline — no leaked "up" count. Poll here too: the gauge decrement
+        // and the stream-count drop are independent observations, so under load
+        // give the finally's SiteConnectionClosed() time to land.
+        AwaitAssert(() => Assert.Equal(baseline, ReadGauge()), TimeSpan.FromSeconds(5));
     }
 
     [Fact]
diff --git a/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/StreamRelayActorTests.cs b/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/StreamRelayActorTests.cs
index c7aa7822..637af4d4 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/StreamRelayActorTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.Communication.Tests/Grpc/StreamRelayActorTests.cs
@@ -279,8 +279,16 @@ public class StreamRelayActorTests : TestKit
         var ts = DateTimeOffset.UtcNow;
         actor.Tell(new AttributeValueChanged("Inst", "Path", "Name", null, "Good", ts));
 
-        Thread.Sleep(500);
-        Assert.True(channel.Reader.TryRead(out var evt));
+        // Poll for the relayed event with a generous timeout instead of a single
+        // fixed Thread.Sleep + one-shot TryRead. Under full-suite CPU
+        // oversubscription the actor may not have processed the Tell within a
+        // fixed 500ms window, racing the read; AwaitAssert retries until the
+        // channel has the item (or the generous deadline elapses).
+        SiteStreamEvent? evt = null;
+        AwaitAssert(
+            () => Assert.True(channel.Reader.TryRead(out evt), "Expected a relayed proto event on the channel"),
+            TimeSpan.FromSeconds(5));
+        Assert.NotNull(evt);
         Assert.Equal("", evt.AttributeChanged.Value);
     }