Ingress with support for websocket

Hello all, I am trying to set up ingress for Signal K for the following webpage app (demo): Signal K Server.

I have set this up in the dev rep here: ha-addons/signalk2mqtt at dev · corvy/ha-addons · GitHub. To test it I suggest you pull the dev rep and save it to the local HA instance in /addons/ folder.

The design is currently that I have created a simple add-on running signalk and nginx. The webpage is presented via ingress the following way: HA → Ingress to port 3030 → nginx on port 3030 → signalk on 3000. When I connect to nginx directly on 3030 the web interface works, if I connect to 3000 it also works. Connecting through ingress I get “cannot connect to server”. My investigations shows that when I connect via ingress websocket does not work. Logs shows for instance this error:

actions.js:162 WebSocket connection to 'wss://' failed:. 
/api/hassio_ingress/…admin/#/dashboard:1 Uncaught (in promise) SyntaxError: Unexpected non-whitespace character after JSON at position 3.

In the SignalK logs I get no significant errors so I think the wss connection does not go back to the addon. How do I attack this? Is it possible to rewrite the wss URL through the nginx reverse proxy? How would I do that and to what? What URL should I use for the wss connection? The url slug looks like this: but that is probably not correct.

Any pointers? Anyone that could help me. You could easily test it yourself by downloading from git and test via the local rep in /addons.

Thank you!