You could switch to Apple TV, BUT make sure the channels you are having problems with are even available on Apple TV first. The channels you mention are "minor" compared to the working channels you mention, and sometimes these smaller channels are just poorly coded. Have you emailed the developers (sometimes that becomes a blame game issue though)?
Yeah, I got some Rokus. https://youtu.be/d1CSEeqWl10
I have the same issue with PokerGO with my 2018 Roku Ultra. Get video playback error every 10 minutes just as you described. I'm using a MOTOROLA MG7550 16x4 Cable Modem Plus AC1900 Dual Band WiFi Gigabit Router with Power Boost and DFS, 686 Mbps Maximum DOCSIS 3.0 -