Even if you didn’t change anything, other players might have. It could be a background change in your own setup or something your ISP did.
For starters: have you verified the manual port forward is working? You can do that using a service like canyouseeme.org. There you can also verify if the public IP seen from the outside is the same as the one seen by Plex‘s remote access settings (and both match that assigned as WAN IP in your router).
The remote access settings are known to show a green status while it’s still performing thr status check (and only turning red after that check has finished, which can be seconds or up to 1-2 minutes later, depending on your setup). I’m not aware of setting changes getting stuck.
