Power management when not logged in on Ubuntu Server with XFCE installed

Hi! Maybe not the most straightforward subject description... I'm in the final stages of testing out my configuration for my new home server that will replace an over decade-old Windows based machine and after about three months of trial and error I'm now really close to be able to install it for real. As I'm not really comfortable with or skilled enough to have CLI only, I have installed XFCE in Ubuntu Server. Problem now is that when not logged in to the system, i.e. when the lightdm login window is displayed (which will of course be most of the time), the machine goes into sleep or hibernation or something like that after 20 minutes. The screen also goes to sleep after 50 seconds, but this is not really a problem, especially since I won't have a screen attached. It will be controlled via VNC and SSH.
After some googling I tried with the "IdleAction=ignore" in /etc/systemd/logind.conf, but this didn't make any difference. Since these things happens at specific time intervals (50 seconds and 20 minutes), I'm thinking that there must be a configuration file somewhere that holds those values and where I can also disable this. But where? It doesn't appear to be in the lightdm configuration either.
The following applies when logged in, but for testing purposes I also disabled the XFCE Power Manager in the "Session and startup" settings. And yet, the system turns off the screen after 10 minutes. What governs this? It would be logical to me that when disabling the Power manager, there would be no power saving. But no...
Can anyone shed some light on this? A sleeping server won't do much...