Youtubetv frequently buffers

I can confirm that TMHI and YoutubeTV can work fine together with no inherent buffering problems.  Assuming you have good, consistent download speeds, your issue may be a weak WiFi connection with your TV.  Your TV may have tests for that, so that's one thing to check. Also, if your SSID for the 2.4 GHz and 5 Ghz channels are the same (which is the default config), you don't usually have control over which channel your TV "latches" on to.  The 5 GHz channel has much less range, and if your TV is latching to that and is not physically close enough to your router, it could definitely cause issues.  In that is the case, you need to force your TV to latch to the 2.4 GHz channel (which has much better range), If your TV doesn't allow that level of control, then you can make a unique SSID for the 2 channels on the TMHI Internet App and connect your TV to the 2.4 Ghz channel.