Unable to connect to Plex except via Web

I have multiple jails running Plex on Core with no problems and wanted to test out Scale. I installed Scale on an old desktop and created a Plex app and loaded it with some music. I can connect to the new Plex server on Scale via the web portal button but that's it. None of my other clients seem to see the server.

Am I missing a step in the configuration of Plex? I'm not sure why the web connection would work but not any of the actual clients.