Trouble with XFCE (trixie) timed logouts

Every few years I upgrade something on my stepper controlled knee-mill. I usually get sucked into upgrading linuxcnc at the same time. I just upgraded the stepper motors and put a new controller on. The new controller is using Mesa 5i25 and 7i76 cards with Gecko drivers. I was running linuxcnc 2.9.4 and decided to upgrade to 2.9.8. Rather than upgrade I did a new install with 2.9.8 (Debian trixie).

After install, and working though several problems, I have linuxcnc 2.9.8 working well with a Pncconf configuration. But, I am having great trouble with the computer logging out every 30-60 minutes. A very bad thing for a machine controller. I suspect this is in the XFCE environment but can not find a solution via Internet searching.

I did find, through searching, and have implemented the following changes:

I changed /etc/ligntdm/ligntdm.conf to implement auto login by un-commenting
  autologin-user-[my user name : hugh]
  autologin-user-timeout = 0

In the XFCE settings I disabled Lock Screen [disable "Lock screen when idle"] and disabled Screen Saver.

To prevent logout from /etc/syslogout I put an empty file as "$HOME/.nosyslogout"

In XFCE setting, under Power Management, assured the "Suspend When Inactive for" was set to never.

I did try, I believe, disabling the Display Power Management toggle in the setting menu. This caused a broken system. When a login was done the machine thought awhile then returned to the login screen. I could not figure out how to fix this via the terminal so had to re-install linuxcnc. I re-installed once without re-formatting the /home directory but the login loop was still present. Another re-install with re-formatting all partitions brought me back to zero. I'm trying to not repeat this error.

The computer now starts up without requiring a  login, that's fine. It works for 30-60 minutes and then logs me out. The result of the logout was a new login screen (user: & password). After the above changes, auto login, it automatically logs me back in. But for both of these, any running applications, like linuxcnc, are killed with the logout/login.

What am I missing? Is there a simple fix or should I step back to linuxcnc 2.9.4 and see if it still works?

I am surprised by this problem. I'd think a linuxcnc ISO should be set up for no screen saver and certainly no timed logout. This seems like death to a machine controller where a complicated program could run for a couple of hours. This tends to convince me I've done something wrong with this new clean install.

Thank you for any help you can provide.

Its actually very difficult to stop this. Been there done that.
You could try running this script with sudo. It creates some system settings that have been working for me.