Plex and mkv has become unusable for me now. Just freezes every 5 seconds and is so annoying. And I'm still paying for this app $4.99 today from my account so about ready to cancel my subscription until the kinks are ironed out. Shame really.
I believe the issue people are having isnt with MKV's (which is just a container format), it's with the DTS audio. Xbox doesnt support DTS and there arent any 3rd party apps to do so, it's all being transcoded by your server.
my plex server is an amd6300 and it still gets bogged down when watching 1080/5.1dts. Playing 720p w/5.1DTS seems to be fine. Only solution I've found is to stick with 720p/DTS or 1080p/AAC files. Not the most ideal, but it works until there's DTS support on xbone
Unless I'm mistaken, the Xbox1 should now support MKV natively since the Novmeber update released yesterday.
I cant say for certain If everyone has it. I'm in the preview program and have had DLNA for some time now. But again, thats just DLNA. It supports MKV files yeah, but not all audio codecs
Also, you mentioned "pausing" issues. Is it literally pausing, or is it slow transcoding? What is your CPU usage at? What are the types of files your playing?
fyi, with the new update, the videos I'm having an issue with play fine with zero pausing through the x1 media player (connected through the Plex server) so it's clearly a transcoding problem.
The stuttering issue is literally down to DTS alone, as I played a film with a both DTS and Dolby 5.1, and it stuttered as usual with DTS. However as soon as I switched to Dolby, the issue went away, and never returned. I hope this isn't an issue that can't be resolved without Microsoft updating the console, as a vast majority of my films come with DTS alone =/