NASes are so annoying. I had so many issues with my Synology NAS with plex and jellyfin. I ended up spinning up a debian server on a small Dell optiplex micro and then mounted my Nas as storage through debian. Installed Jellyfin as a normal debian package. No docker or anything like that. I’ve never used (or even heard of) QNAP, but are you able to reach it through SMB? If you can, then you can do it like I did