I’m currently a Plex user and access it from Apple TV’s. I find this is a smooth and stable experience that everyone in the house enjoys and is comfortable. I also use PlexAmp on laptops, mobile and CarPlay.
I am interested in Jellyfin and am wondering if I can expect any hurdles or rough edges moving over?


Be wary that high bitrate 4K media may cause issues with playback buffering.
This could be Jellyfin, AppleTV, or it could be network/storage related (due to needing high speed data transfer).
I second using the Infuse app for playback. It works wonderfully!
Really interesting that you’ve encountered this, I have no trouble at all watching super-high bitrate media in Infuse. I may be spoiled with my gigabit internet, but the Apple TV caches entire 4K Blu-rays in minutes on my local network (you can watch the seek bar fill up, it’s really satisfying) so I never thought about this. I’m curious why this hits some users and not others.