So I actually had this exact issue about a month ago.

Solution: You have to connect to chromecast through your phone app. However, the jellyfin app have to be installed through play store. If you install it through f-droid or similar it won’t work.

Took me about a month of troubleshooting to find that answer. :D

What other plattform would you suggest?

Does that include videos?

Not to be that guy, but it is the 2038 problem for 32 bit epoch. Check this out: https://en.m.wikipedia.org/wiki/Year_2038_problem

But yeah, that’s a much bigger issue.

The minute i saw that was the minute i changed away from those types of backgrounds on the login screen. In the control panel you can just change it to anything you want