I rarely use my Xbox 360 Plex app, but last week when I attempted to play 1080p content, it failed …even though the same content played just fine using DLNA. My server is running version 0.9.15.2 on an i7 Haswell.
My server is an Intel Core i7-4770 Haswell. It transcodes very well on my other devices and also remote viewers. The server isn’t being overworked, and the Xbox is wired, not wireless.
Close the Plex server, restart it, wait about two minutes, connect with your xbox and try to play a movie that causes problems. Wait about one minute, then close the xbox app and shut down the server software. Grab the logs and post them here.
I was able to play a different 1080p file (MKV) with no issues, so it must be something with the MP4 file I was trying to play before. Like I said, I can still play it using DLNA. It is only a video calibration file anyways…not that important.