I found this in another thread:
I was just able to start the sever manually with the following command via SSH:
sudo /var/packages/RoonServer/scripts/start-stop-status start
Server is up and running.It’s not showing in the UI that it’s running but Roon finds my core again. So at least there seems to be a workaround.
see here: Roon Server on Synology DSM 7.0 Preview - #2 by Jonathan_Fallows
Hope it works for you too