There have been no recent changes to Plex Media Server in this area. So a problem arising after an update is a coincident and could be just different timing or some other things changing as well
Recent Remote Access failures I have investigated were caused by:
- xFinity xFi Advanced Security
- xFinity Port Forward not working and Port Triggering used by user
- Server migrated from another system and machine identifier copied across but this was done when the server was claimed by an account and ended up having a machine identifier that does not match the security token (There was recent change to strengthen token validation)
- infrastructure issue on plex.tv backend systems used for remote access connectivity testing. This was addressed and resolved
