Jellyfin is avaliable on almost everything as far as I am aware (excluding games consoles). Havent used Plex much but I know for Jellyfin the majority of my users issues relate to iOS. Id check your encoding of the specific file they have issue with M series macs can be weird with certain encodes of h.264 for example or a specific audio type. Here is a decent breakdown of codec support by client/browser https://jellyfin.org/docs/general/clients/codec-support/
Jellyfin is avaliable on almost everything as far as I am aware (excluding games consoles). Havent used Plex much but I know for Jellyfin the majority of my users issues relate to iOS. Id check your encoding of the specific file they have issue with M series macs can be weird with certain encodes of h.264 for example or a specific audio type. Here is a decent breakdown of codec support by client/browser https://jellyfin.org/docs/general/clients/codec-support/