That depends a lot on what you're hosting resp. if the mobile apps are using Google's/Apple's messaging/notification services.
JASN_DE
Not sure if it makes things easier than your current setup, but take a look at Mediathekwebview.de
How are you running Jellyfin?
Running NC on the same instance for the last 4 years on docker. Both point versions and major version upgrades work fine, as long as you take care to check for 3rd party app compatibility.
Not running "latest" and not auto-updating helps.
Hetzner
Use the web console and check which IP the machine actually has.
You can use -f /path/to/compose.yaml to call it from wherever you like.
Is he going to offer miniature submarines and call people pedos again?
If you're already familiar with it and can maybe even reuse some compose files, it's definitely worth it. Even on a Pi.
What did I do wrong
I was configuring some network stuff
Unless you knew exactly what you were doing, chances are good you're currently without a working network connection, I.e. the machine is likely running, but not being able to connect to it will have the same effect as it being powered off.
Unfortunately the steps to fix that are even "worse" than for a machine that's simply powered down. How long will it be until you're back in your home?
how do y’all handle rebooting your bare metal when you don’t have access to the physical server atm?
I simply don't. At least not those that aren't covered by idrac etc.
The official NC docker container uses the "www-data" internally to run the services. This will get important if you ever want to run tasks via "docker compose exec".
Have a look at kimai.org
The have a self-hosted option and apps (didn't test those though).
Always remember: RAID is not a backup.
Having only one backup and the server dying means you now have no backup, therefore the 3-2-1 scheme for backups is worth looking into.