diff --git a/sources/Google.Solutions.IapTunneling/Iap/Messages.cs b/sources/Google.Solutions.IapTunneling/Iap/Messages.cs
index 2919268ea..27c02baec 100644
--- a/sources/Google.Solutions.IapTunneling/Iap/Messages.cs
+++ b/sources/Google.Solutions.IapTunneling/Iap/Messages.cs
@@ -97,7 +97,9 @@ public enum CloseCode : int
         DESTINATION_READ_FAILED = 4010,
 
         INVALID_DATA = 4013,
-        NOT_AUTHORIZED = 4033
+        NOT_AUTHORIZED = 4033,
+        LOOKUP_FAILED = 4047,
+        LOOKUP_FAILED_RECONNECT = 4051
     }
 
     /// <summary>
diff --git a/sources/Google.Solutions.IapTunneling/Iap/SshRelayStream.cs b/sources/Google.Solutions.IapTunneling/Iap/SshRelayStream.cs
index fe2cb792c..69945b42d 100644
--- a/sources/Google.Solutions.IapTunneling/Iap/SshRelayStream.cs
+++ b/sources/Google.Solutions.IapTunneling/Iap/SshRelayStream.cs
@@ -252,7 +252,9 @@ public async Task TestConnectionAsync(TimeSpan timeout)
                 }
             }
             catch (WebSocketStreamClosedByServerException e)
-                when ((CloseCode)e.CloseStatus == CloseCode.NOT_AUTHORIZED)
+                when ((CloseCode)e.CloseStatus == CloseCode.NOT_AUTHORIZED ||
+                      (CloseCode)e.CloseStatus == CloseCode.LOOKUP_FAILED ||
+                      (CloseCode)e.CloseStatus == CloseCode.LOOKUP_FAILED_RECONNECT)
             {
                 //
                 // Request was rejected by access level or IAM policy.