Plex "Server is unreachable" on host hardware

Hey guys, I'm getting an error with my Plex server since this morning. It's "The server is unreachable" error, where nothing is accessible. Funny thing is that I'm getting this directly on the server as well as remote. When I navigate to the IP: port/web address, I get asked to select the user, and then I see the sidebar with settings for the plex web interface, and my server settings in the sidebar show as Server unreachable.

I'm running on Ubuntu 18.04 with all of my programs running in docker containers. I've been running this setup for about a year now.

I had to power down the server yesterday evening, and today when i powered it back on, everything else seems to be working save for this error with plex. Not really sure where to even begin to troubleshoot it. I've gone through all my other containers, and I've not found any other ones misbehaving.

Portainer is reporting plex as a healthy container. I have restarted the whole server, and it is presenting the same issue. None of my other containers are having issues. It's only Plex that's giving me grief today.

Whether I'm on the server hardware or on a different, remote, PC, I get the same Server unreachable message using the IP: port/web. Logging in via plex.tv asks me to select one of my home user accounts, and then it shows "No media found".

I have tried to rebuild the container, but since the data carries over, this didn't change anything. I'm open to suggestions. Last thing I want is to have to start all over again.