Given the steps already completed, the most useful next check is Event Viewer immediately after the unwanted power-on.
- Open Event Viewer → Windows Logs → System.
- Look at entries around the exact shutdown/restart time for these event IDs:
- 41 (Kernel-Power)
- 6008
- 1001
- 1074
- If 1074 appears, check the recorded Shutdown Type and the process that initiated it.
A key distinction from the available guidance:
- If the system is coming back because of a forced power-button action, Windows can log Event ID 41 with a nonzero PowerButtonTimestamp.
- A dirty shutdown or forced power-off can also be associated with Event ID 41.
Based on the documented behavior, an immediate power-on after shutdown is not explained by standard Windows wake behavior if the machine is truly reaching S5 soft off. Wake-on-LAN is supported from S3 sleep or S4 hibernate, but not from fast startup or S5 soft off shutdown states. Some BIOS implementations may still arm the NIC for wake independently of Windows, but Windows is not involved in that process.
For Windows-side troubleshooting that is still supported by the available guidance:
- Check Device Manager for any device with an exclamation mark and update, disable, or uninstall the affected device.
- Install the latest Windows 11 updates from Start > Settings > Windows Update.
- If the issue continues, start in Safe Mode and test shutdown behavior there.
- If shutdown/restart problems persist, use Recovery options in Windows 11 or a system restore point.
If Event Viewer shows BugcheckCode = 0, no minidump, and no BSOD, the documented Q&A guidance points more toward a hardware or firmware-level reset/power event below the OS than a Windows process or hidden registry setting.
- Intermittent Automatic Restart Issue When Selecting Shut Down in Windows 11 - Microsoft Q&A
- Advanced troubleshooting for Event ID 41: "The system has rebooted without cleanly shutting down first"
- System power states
- Troubleshooting Windows unexpected restarts and stop code errors
- Random Restarts - Fresh BIOS & Windows Install - Microsoft Q&A