Slow connections. iOS connection error
95% or more of these are due to improperly configured reverse proxies where the WebSocket is not working properly. If a WebSocket cannot be correctly established, the client will try and fall back to an XHR connection. It is extremely slow and flaky. The iOS app will not connect at all without a WebSocket.
Always use chrome and dev tools to check for the presence of a WebSocket.
WebSockets
Right Click, Inspect
Network, F5 to refresh
Look for the WS filter
Should see WebSocket( wss://open.rocket.chat/sockjs/123/pbiz45rm/websocket)
Click it and look on the right for 'Headers'
Has this got a green light?
Status Code: 101 Switching Protocols
What do the headers say?
Response headers
Connection: Upgrade
Sec-WebSocket-Accept: nXd/PfaHuA1Kx/ggJWAAy+96Ee4=
Upgrade: websocket