Apple TV 4K stuttering playback from airplay

airplay/screen mirroring from camera roll/videos produces awful results on the big Screen with consistent stuttering picture.

I've tried a million different things to figure out the problem. Software update, reset, change HDMI cable, change rooms, change devices streaming from, check internet provider (Albeit my videos are NOT streaming from iCloud they are on my PHONE). I’m using iPhone 8 plus with latest software. Yes I’ve rulled out all individual issues and it’s still a puzzle. Apple geniuses were equally confused in store and replaced my Apple TV 4K TWICE. Yes I am on my third Apple tv and extremely frustrated. This is inherently an Apple TV 4K problem that needs way more attention that’s it’s currently getting. I was told in store they have not seen anything like it before, yet I got three Apple TVs in a row with the same issue?? How infuriating. I don’t even want another replacement. I’m so upset that I just want my money back. Airplay/screen mirroring is of high importance to me and I consider it money wasted if I can’t have quality streaming on this device.