How do I keep Fedora to try to suspend my system when idle?

I have a Fedora Linux system under my desk at home. It runs the Workstation setup (with GNOME) even though it mostly is used headless. It is my file server (samba), mail server (dovecot, mailman) and webserver (apache, perl-cgi). But recently,I am using digiKam to manage my photo connection, and I do this from a GNOME session. When I upgraded to Fedora 40,

started shutting down (suspending) the system when idle, which of course prevented my server services from accepting connections. I fixed this with

mask suspend

and

mask sleep

. But recently, this is not enough: When I am logged in remotely by

, I will get interrupted every minute or so with

Broadcast message from root@cleo.beagle-ears.com (Mon 2025-04-14 15:07:31 PDT):

The system will suspend now!

How do I get rid of this?