Very odd indeed.
What worked for me was to:
- Stop Plex server
- On iPad, Delete iOS app
- Reinstall iOS app and perform initial login / setup
- Select alternate profile (if using same profile the error would come up even while server was offline)
- If successful, restart Plex server
- On a computer to go Plex Home, remove PIN from the user getting the error.
- On iPad, Kill Plex app on iOS and relaunch - try offending user without PIN, if successful,
- On iPad, Kill Plex app on iOS
- On a computer to go Plex Home, ADD PIN back to the user
Fixed 2 Gen 5 iPads rockin iOS v16
