Why Your Unity WebGL Multiplayer Breaks on Some...

You test your Unity WebGL multiplayer game. It works perfectly. You share it with a friend — it works. You share it with someone on a corporate network, or a phone hotspot, or after pushing a new build — and it silently fails to connect. No useful error. No crash. Just... nothing. This happens because Unity WebGL multiplayer has three distinct failure modes that don't exist in standalone builds: CORS blocks the connection before it opens, WebSocket gets intercepted by a network proxy, and browse