UPDATE: Deleting the app on Fire TV Cube seems to be working. Thanks for the insight, Macaroni_Apple.
Server: Mac Mini - Plex Version 4.50.1 (macOS Catalina)
I am having the same problem. Basically, the exact same thing.
At home we have (2) 2020 2nd gen Fire TV Cubes (running Fire OS 7.2.2.9) for serving a lot of media. One gets used for everything and a very high frequency with Plex, much with a friend’s shared libraries.
There hadn’t been any issues until the last week or two after I updated to the latest version, cleaned, added and overhauled my Plex library and updated to the macOS.
Initially, I thought the VPN was switching on and blocking the server.
Messages between the Mac Mini and the Fire TV Cube read things including:
-Something went wrong
-There was an error loading your home screen.
-No content available
-Error loading content
I realized that the server was absolutely crashing every time it was being accessed, even if it was just from another room.
I spent hours today troubleshooting including deleting and reinstalling Plex, adjusting all app settings, deleting and reinstalling libraries, checking all router issues.
Every time I’d go back and restart it, it would eventually crash again. After accessing server on the laptop and from apps on several iPhones, an iPad and the Samsung Smart, I was able to narrow it down with certainty that the crash was happening from the Fire TV Cubes.
And it crashes EVERYTHING in the server including the Remote Access setting.
Tried using a different browser and resetting the homepage but that didn’t help. Will try deleting and reinstalling the app on the Cubes tomorrow.