My support also goes to Jellyfin but I have both plex and Jellyfin running because occasionally Jellyfin will have a playback error that I’ve tried to but failed to diagnose. Have yet to have any playback errors on plex, but again my go to is Jellyfin because it’s local, the UI is more customizable and in my opinion the UI is just better.
I can’t remember the last time I’ve had a playback error on Jellyfin that wasn’t related to my power going out and my NAS not coming back up (thus Jellyfin not having an actual video to serve). Jellyfin has been incredibly stable for me.
Unfortunately I can still reproduce the errors. Happens with a few shows but only when using the Jellyfin app on a fire stick. I’ve never had any playback issues using the Jellyfin app on my Roku TV. So, in those very few situations, I just use plex.
It sounds like a codec error. I would bet that if you checked the files experiencing the errors it would have some esoteric codec or be a format your host can’t easily decode, or it’s a format the playing device hardware can’t decode but the Jellyfin player doesn’t know that (somehow Jellyfin isn’t getting correct info).
I’ve had that before with a really old avi file with divx. I re-encoded the file to MP4 with h264 and it works perfectly.