I just wanted to post this solution here because I encountered the “Claim Server” button not working problem today.
The reason afaik from my searching this happens is because the Plex media server can’t contact the plex.tv servers. For myself, I don’t know what changed in my network setup - possibly that I asked my ISP to remove my account from using CGNAT because it kept interfering with PMS being accessible via the internet - but something changed and after I reinstalled/reconfigured/logged out/retried umpteen different things I ended up at a point where everything was working except I couldn’t claim my PMS to my Plex account. Clicking the Claim Server button would either just do nothing, or send me in a page loading loop back around to the Claim Server button again.
One solution is to check/resave your /etc/hosts file. Mine had nothing in it to do with plex.tv hosts (some VPNs alter this file) and re-saving the file did nothing.
The next solution is to force the machine running PMS to use google’s DNS servers. This is what fixed this problem for me.
On a QNAP TS470 Pro, to change the DNS server settings you have to go through like a settings wizard for the network interface the machine is using to access the internet. To do this, log into the QNAP via the web admin interface, then go to:
Control Panel
Network & Virtual Switch
Locate the adaptor that has the IP address of the PMS (mine was like, 192.168.86.200)
Click the overflow menu in the top right of that area (the 3 vertical dots)
Click Configure
This will open the settings wizard for that network adaptor and after a few steps you can tell it to manually use google’s DNS servers which are: 8.8.8.8 and 8.8.4.4
Finish the wizard and you should now be able to click “Claim Server” and it should work.
Also note: in that wizard you can disable NAT, which if you have trouble with accessing PMS from the internet could be relevant. My network configuration is: QNAP with PMS on it → Google Wifi Router → Broadband Modem → ISP → Internet
The Google Wifi Router does NAT and my ISP does NAT (CGNAT). And it seems like maybe the QNAP was doing NAT as well. As per the Plex documentation found online, too many devices doing NAT stuffs up accessing PMS from the internet. So I requested my ISP disable my account from using CGNAT at their end, and I just turned off NAT on the QNAP, so hopefully on my Google Wifi Router is doing NAT now and hopefully it all works from now on.
