Recently, I keep finding my PC is turned on when I come downstairs in the morning. I thought it was failing to power down when I press the power button and walk off for some reason, but I've proved it is actually shutting down, then spontaneously turning back on. It did it just now in fact, I was in the room and suddenly my PC turned itself on!
I turn it off using the power button on the chassis, which hibernates the PC - i.e. a totally powered down state, the fan stops, all lights go off, I hear the 'clonk' as everything stops. It is not asleep or in standby.
I know boot-over-ethernet is a thing, but I have not tinkered with the bios and it has only recently started doing this. Could it be that some malicious user is booting my PC remotely? If not, what other possibilities are there because this is not just annoying but a little concerning.