I recently got a PlexPass and have set up a RasPlex in a second house, which I signed into with my account. It's running fine, however I am not sure how I can get a remote control via Android to connect, as there isn't a server on the local network.
I'd try the latest rasplex (9.9.17) and the latest android app.
I think that sometimes a local server is helpful for the app to find the player, but realistically it shouldn't be needed (i don't think...), since gdm should take care of it.