AppleTV 4K buffering constantly

Hey Apple community. I have an appletv 2nd gen (4K), having seemingly odd buffering issues across all streaming services.

streaming randomly swaps between clear and blurry just about every 5-15 seconds, more or less. Almost as if the connection isn’t strong enough to support full resolution, so quality drops while it buffers, then goes clear again for a few seconds. Occasionally the show pauses as it buffers. This occurs on Netflix, Hulu, spectrum Tv app, hbo, Amazon prime video and driving me bonkers :)

gear and basic trouble shooting: Internet is spectrum, clocking at around 500mps. we use google mesh router pods, 6 of them (2260 sf house, one story) one pod typically right under the appletv or within the bedroom (moved this around as part of testing/troubleshooting). All other computers, iDevices, smart devices etc in this bedroom work no problem. Vizio 4K tv UI has no issues on streaming services. Have done resets on everything, along with tried a new modem altogether and factory-reset the entire mesh network twice.

today I swapped out hdmi cables but not sure if the cable is Dolby or not. Current HDMI input on TV is labeled 4K at 60hz, and AppleTV video format selected is 4K SDR 60. I have switched this to another input which is labeled 4K at 30hz and it seems to resolve the buffering issue however, when I switch inputs, appletv format drops to 1080 SDR.

any explanation as to what is going on here might be helpful. I’d like to resolve the issue and maintain 4K if at all possible.