Error during WebSocket handshake: Unexpected response code: 403

[NVentimiglia]

WebSocket connection to 'domain/ws' failed: Error during WebSocket handshake: Unexpected response code: 403

I am trying to understand this error. It is not appearing on localhost at all, so, I think the package code is fine. It is appearing on my websocket enabled IIS stage server. I tried opening a support ticket as well as googling to no avail. If you could be so kind as to point me to some possible causes I would be so happy.

The app is an MVC 4 app.

[lixiaoyuan]

I am replay 2oo error.
WebSocket connection to 'ws://localhost:8022/' failed: Error during WebSocket handshake: Unexpected response code: 200