diff --git a/Assets/Mirror/Core/NetworkServer.cs b/Assets/Mirror/Core/NetworkServer.cs
index 5d545e15f..69ac7cf94 100644
--- a/Assets/Mirror/Core/NetworkServer.cs
+++ b/Assets/Mirror/Core/NetworkServer.cs
@@ -1266,6 +1266,11 @@ public static void SetClientReady(NetworkConnectionToClient conn)
         {
             // Debug.Log($"SetClientReadyInternal for conn:{conn}");
 
+            // only if not already ready yet.
+            // prevents clients spamming ReadyMessage to force observer rebuilds.
+            // fixes: https://github.com/MirrorNetworking/Mirror/issues/2623
+            if (conn.isReady) return;
+
             // set ready
             conn.isReady = true;