Remote Access not working, despite port forwarding

Did you already have a look at the related troubleshooting support article?

https://support.plex.tv/articles/200931138-troubleshooting-remote-access/

There’s also a guide with some more details on how to troubleshoot remote access issues.

Personally, I would start testing

  1. If a service like canyouseeme.org is able to see the published port on your router
  2. If the IP recognized by that site matches the public IP listed in your server’s remote access settings and your router’s WAN IP.