I will to try make a PS4 downgrade… Ideas???
Just is freezze there
As I already mentioned in the other thread about this (still ongoing and annoying issue), I’m pretty sure that I was able to use Plex after the upgrade at least one or even two time before the very same problem that you captured occured to me (and as one can see in the other thread also many other PS4 App user). Hoiwever, if you downgrade the PS4 system, and this would solve the problem - please let us know 
Good luck!
If you know a solution to downgrade a PS4, let us know!
The Sony support don´t recommend a system software downgrade and I don´t search for it anymore. The problem was solved by other Plex user, changing the DNS´s ips in the PS4 to Google´s DNS (8.8.8.8 and 8.8.4.4).
