Having a similar issue - admittedly haven’t actively used my plex server for about 6 months (since the pandemic really hit the U.S.) but I have run the program to update it, which I believe it’s running the most current version.
All of a sudden I’m having terrible issues with “not available outside your network” messages…typically I would just disable my Norton antivirus and the Norton firewall for a few minutes, disable remote connections and then enable and it would be fine.
Now, nada. Doesn’t matter what I’ve done, nothing changes. It’ll be “available” for about .02 seconds then goes back to red/not available outside your network.
Definitely looking to find a fix for this asap as well