Setup like described - but "Establishing connection, please wait.."

[ctc]

Setup with nginx / proxy_pass as described.
Websocket log:

down: 0{"sid":"dUPskU726Iye118fAAAB","upgrades":[],"pingInterval":25000,"pingTimeout":5000}
up: 40/socket.io?token=xxxx
down: 42["user.joined",[{"displayname":"nadmin","permissions":27,"userid":"xxx"}]]
down: 44/socket.io,"Invalid namespace"

no idea if "Invalid namespace" causes the problems?