Ah, it’s one of those. I was thinking it was the TV’s OS.

I don’t have a lot of experience with those smaller dongles, but as I understand it they’re fairly low power devices that are more meant for streaming relatively low bitrate media from the internet or from a phone. It may not have the horsepower for playing back high bitrate media from Jellyfin or Plex.

Others may have a solution that’ll work for that device, but my gut response is to say you should consider replacing it with something more powerful.