As pkulak said, Nginx didn't understand the Upgrade header so you couldn't proxy http and ws connections on the same port. To get around that you had to add ei

As pkulak said, Nginx didn't understand the Upgrade header so you couldn't proxy http and ws connections on the same port. To get around that you had to add either another reverse proxy that did offload ws:// connections or run them on separate ports and deal with issues like corporate firewalls.