@ashley_r361
Your first dig shows udp 512 indicating something molested the packet. If you don’t have a reverse proxy or pi-hole then your router or isp is messing with the lookup. You are also running an un-supported Pi5 OS which may conflict with the binaries in Plex.
Everyone else jumping in here with a “me too”, if you don’t include the zip of your log files preferably from 3 minutes after you have restarted Plex Server then there isn’t much that can be done for you. Also a screenshot of Server>Settings>Network to show that you haven’t entered in incorrect info into the fields would be helpful.
If Plex can’t setup a secure connection to it’s servers (plex.tv) then it can’t validate if you have a Plex/Remote Pass and let the client connect.
