I have a debian box physically in another location, and would like it to stay online. I put a fresh install on it, including gnome, then rebooted it without a display attached, with the plan to ssh into it later. After about 20 minutes, it disappears from my router page (via vpn, all other devices are still connected) I turned off all sleep settings, so the 20 minute timeout should be never, as is the idle setting and what "closing the lid" does in gnome tweaks.

Any way to make it stay online?