technology

Scho docker by default runs on a separate network and resulting IP entirely unless you bind it to the host network or use a reverse proxy. The Plex docker also has a host network setup which I imagine handles this for you which you should try because it will act more like a normal local service. If you have a firewall that is catch all then it will block the docker IP which is something I bashed my head against for a while. If you wanna debug where your service is running there is netstat command eeeer. -tulpn I fink need to go get my laptop. Then you can list all the IPs and ports bound and find where Plex is running and work from there

sudo ss -tulpn

Or

sudo lsof -i -P -n

This sounds like it's a networking issue. Are you able to access the webui from other computers besides the computer that Plex is running on?

The linuxserver docs have a snippet on configuring networking for plex.

your container group and user id can run into networking issues if you responsibly denied the access to everyone (guest) except for current user (this is in environment variables, if I recall correctly, you can go to admin numbers of gid/pid, check if it fixes stuff, and then deescalate them to something working, i think container can’t claim privileges higher than docker itself, so there is some shit to troubleshoot there)

check that your firewall on the server is not blocking (or clashing, check with netstat) port range you use and/or docker itself (i once run into firewall rule blocking python in the thingy i was using, that wasn’t fun), rebind the port to different one in any scenario, reboot, check again.

check router firewall rules for local networking, check you are using correct ip of server (check you can ping server as an entity, bind it to static in router, and remove old leases, reset router if you can’t remove old leases).

this is general order i fumble containers when i forgor

(also, you can enter into terminal from inside the container, and check out what it sees networking wise)