This is almost certainly a you problem. Tons of people play remuxes with Jellyfin. I would check that your client supports the requisite codecs, and has a suff

This is almost certainly a you problem. Tons of people play remuxes with Jellyfin. I would check that your client supports the requisite codecs, and has a sufficient network connection. Or alternatively check that your server has enough horsepower (GPU or CPU) to transcode.