If you are powering your Roku by plugging into the USB port on the TV, try powering from house power via the USB power adapter that came with the Roku.
The ports on many televisions only supply 0.5 amp or less, which is not enough to power a Roku reliably. It may appear to start up okay, but when it runs into something that requires more power than the tv's USB port can provide, something's got to give. Frequently this results in shutting down the stream you are viewing and exiting back to the Roku home screen.
If this is a new problem, possibly an update to either the Roku operating software or to some channel app software is using a little more power than in the past, triggering this problem.
If you don't have a Roku adapter handy, any other you have from another device should work as long as the fine print on it says it outputs at least 1 amp.
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well. If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X
Re: Roku express will only play for 3 minutes then stops
Not that I'm getting much help but just to update...
I tried a factory reset and I still have the same thing happen.
It's pretty **bleep** that my device doesn't even qualify for even a chat with Roku customer support to try to fix a device of theirs that I paid money for and I'm left begging the Roku community for support that I should be getting from Roku.