To shut it down, the remote command posted by @mjw works. Though of course simply clicking shutdown on the web admin page also does. For more convenience you can automate the shutdown command: Roon 2.65 - it was faster for a while, not so much after a while - #152 by Atiss
When the OS is shut down, a start timer in the OS won’t work. This has to be at a lower level, and therefore the BIOS has an option: enable WakeOnLAN in the BIOS and send a WakeOnLAN command from another machine. There are apps for that or you can run it from the command line.
Consider that
- Running a NUC 24/7 costs a few euros per year
- The Roon Server performs maintenance such as metadata updates even when you don’t use it actively. This can take several hours and it can affect performance, which is why Roon recently introduced an option to schedule this maintenance to a time window outside of listening hours. If you turn it on only then you use it, this maintenance will run precisely when you’d like to use it.