SOCD report detected: (AP watchdog expired)

When does the Mac mini throw-up that message and restart...?

1) If after wake from computer sleep, test the following settings and steps:

Turn On "Prevent automatic sleeping when display is off"

Set "Turn display off when inactive" to 5 or 10 minutes

Leave the iMac On and only allow the display(s) to turn Off

Do not manually Sleep from the Apple Drop Down menu

Only Shut Down the iMac when away for a day or more

2) if it restarts at other random times...?

Download and run the free version of EtreCheckPro, from > https://etrecheck.com/en/index.html

Then post your Report, as per > How to use the Add Text Feature When Post… - Apple Community

If it is a connected DEVICE, all you can do us unplug them and reconnect one at a time until the issue returns.

In addition to devices, a connected SERVER like OneDrive, Carbonite, etc, can cause that if it is down when the computer polls it or tries to read or write files.