SOLVED: Can't stream until logged in (Linux)

[Poppy0260]

Hello,
I recently installed Jellyfin server 10.10.6 (deb) on my laptop, love it. Laptop is running Kubuntu 24.04. I am only ever streaming on my home network to my chromecast or android devices.

I would like for family members / children to be able to power on the laptop when they want to watch something on the TV. I don't want to leave it on 24/7. But I also don't want to give everyone in the household user access.

My issue is when the laptop is powered on but left at the login screen, our device apps can browse the libraries, but not play any media. When I try to play, I get this error:
   
Playback Error - Playback failed due to a fatal player error.

After I log in to Kubuntu, then everything works great. And it will continue to stream media correctly even if I then log out and leave the laptop on the same login screen.

I found the logs in Jellyfin dashboard and the failed stream logs end with these lines:

Code:

[in#0 @ 0x56ae18f62740] Error opening input: No such file or directory
Error opening input file file:/media/<username>/Data/Movies/The Bourne identity (2002)/The.Bourne.Identity.2002.mp4.
Error opening input files: No such file or directory

I thought it might be a permissions issue, so I added permissions for user jellyfin to the /media/<username>/Data/Movies folder. Didn't seem to help. The mount point is owned by root, not my user.

Now I think it is a mounting issue. I don't see my "Data" partition listed in /etc/fstab but I can see it in KDE Partition Manager. It also gets mounted by other users logging in. I don't know if there is a way to have it auto mount at system boot, should I add it to /etc/fstab?
   

Many thanks to anyone who can point me in the right direction!