In another thread about this same issue, Roku announced they believe they have solved the problem, and if you restart your Roku (suggest actually unplugging it and then powering it back up) they feel it will work correctly. Can't hurt to try.
Go to settings>network>bandwith saver and turn off. It will stop it from kicking you off a channel automatically. And it sounds like yours is glitching.
Similar problem here, Roku app streams for a few minutes then stops and returns to the home screen.
Stick is brand new and works perfectly in every other way, no issues with iplayer, youtube, both great in 4K