Stop other services when jellyfin is running

Is it possible to stop/pause other services when jellyfin is being used?

It can be, but it may have undesired effects.
What is it you are trying to do? You can raise the priority of jellyfin against other process if you need this.

I have gleutun and transmission running in docker on my “on the road” pi. It host jellyfin to watch my media where ever I find myself. I find if transmission is running jellfyfin is glitchy. If I pause transmission jellyfin runs great. Just trying to automate the pausing of transmission.

You can try to go to jellyfin service from dietpi-services, edit it, and add the command to stop transmission when jellyfin starts, maybe with ExecStartPre= and restart it at ExecStopPost=
https://www.freedesktop.org/software/systemd/man/systemd.service.html

I will give it a whirl.

But this would mean to start/stop Jellyfin manually.

Probably better to use something like our Dashboard and stop individual services if needed from web UI

Yes…that makes sense…will just pause transmission from the url for now.