Nvidia Shield plugged into my TV running Jellyfin. Occasionally if I get playback issues I'll open with an external player like Just Player, Vimu, VLC, etc.
Jellyfin used to be pretty rough with playback, especially if you watch with subtitles, but in recent months I've rarely had playback issues.
On PC I use mpc/madvr, but usually just to check a video file, not to watch a whole movie. I save that for the TV.
I've been having the same problem even on my home IP. It only happens when I'm using Firefox though. If I use Chrome, and oddly enough change my IP by routing through my rented VPS and pass a few captchas then Google will eventually start to trust Firefox from my home IP. It's bizarre and Google is really starting to piss me off because I'm wasting so much time on this shit.