After many attempts, many re-installs, many sleepless nights I implore your greatest attention on this topic.
I had PMS successfully running on my TrueNAS Scale machine as a kubernetes pod.
It worked well, the install and config was easy and bare minimum knowledge required, I was actually surprised that it worked out on the first try.
Couple of months later, the pod wouldn’t start, and so I started checking the logs and noticed it wasn’t able to download the PMS binaries from the online repo (under official plex.tv servers).
I started checking on my firewall UDM for anything firewall related, or DNS related. Nothing would indicate firewall rules blocking or any other Network issues.
So as any other person with common sense, I tried getting away from TrueNas (as it was never my intention to install any Services besides File Sharing solutions on it) and installed PMS on a fresh new deployed Ubuntu 24.04 machine.
And at this point I got the well-known “Not authorized” page and it started becoming frustrating.
Could not find anything… until it was clear to me
I noticed that it was clear that somehow, I could not reach official plex.tv servers thru the WAN. And this becomes a crucial step to download plugins or even the most basic → CLAIM THE SERVER TO YOUR PLEX ACCOUNT!
I tested this with a simple telent plex.tv 443 on 2 completely different networks with diferent public IPs.
The results: telnet successfull on a different network (family home), And no response on the network where PMS is installed.
Conclusion:
Well, it could somehow be, that my ISP decided to block the connections going to the plex.tv servers on port 443. 
Or maybe I’m just really stupid and tired, and it might be something really easy to fix.
Anyway, I tried all options, I’m a SysAdmin with 5 years experience, I work on a Cloud provider, and somehow I am not able to find the root cause, nor find a workaround for this. I am done. 
