Unable to use behind proxy.

I'm using the Docker-compose but modified so that the ports are not exposed, I did not want to expose the ports on the network unencrypted, so I set up a nginx proxy with letsencrypt.
On the proxy I send traffic from port 443 to http://dockername:4326
I can get to the admin page with no issues but it does not seem to want to connect to the socket.
I have a suspicion that the actual webbrowser attempts to connect instead of internal in the docker container. Is there a way to configure it to connect internally or do I need to expose the port outside the continer?

Start by reproducing the modified Docker Compose setup with nginx and the HTTPS proxy from port 443 to port 4326. Trace how the browser establishes the socket connection and verify whether the proxy forwards it correctly without exposing the container port. Done means the admin page and socket both work through the proxy.

Written by the indexing model from the issue text.