It looks like is a configuration problem. When I load the page, there is this network error:
socket.io.js:8 WebSocket connection to 'wss://example.com/socket.io/?EIO=3&transport=websocket&sid=zV8kYkx-87ULGIjGAAAF' failed: Error in connection establishment: net::ERR_SSL_PROTOCOL_ERROR
On Chrome's inspector window it says it was canceled.
But then it works normal.
So all I need is to bypass the first error... or even better, fix it.