Real-time text collaboration server is unreachable

[tapashdatta]

I am using docker compose latest 17-slim docker image.
But whenever I go to real time document edit, I am keep getting this message.

Unable to open document because the real-time text collaboration server is unreachable. Please contact the administrator if the problem persists.

[allenchen013]

I got the same problem, and the hocuspocus container return the log message "[onAuthenticate] fetch failed".

I am trying to deploy in a Synology NAS with reverse proxy server.

[abraxaswd]

Connecting to the server results in exactly the same error here too "[onAuthenticate] fetch failed".
accessing the url in the web browser returns "Welcome to Hocuspocus!".
I use traefik in front of the openproject based on the githubs docker compose file.

[abraxaswd]

I was wondering on how the connection between hocuspocus proxy and web container are meant to be created. As in the actual setup, connections are forwarded coming from the internet via reverse proxy (in my case traefik) to the proxy container (caddy) of openproject. Accessing the hocuspocus container seems to use the url in the env-file and the caddy-proxy should forward /hocuspocus* to the hocuspocus:1234 container and port. This works in my case i can see the running hocuspocus when accessing https://subdomain.example.net/hocuspocus.
This seems to be the result of the caddy file forwarding /hocuspocus to the right container. Accessing the document always results in an error. my question is, how is this connection created? Does the web container connect directly to the COLLABORATIVE_SERVER_URL in the env-file? in this case wouldn't it be the correct way to set it to https://subdomain.example.net/hocuspocus. so it should terminate outside on the reverse proxy and then be forwarded.... Maybe someone has a link to the documentation or some hint on how this is meant to work. Thanks in advance.