“Windows 10 will sometimes start a totally shut off computer on its own to install updates.”
It’s called Wake On LAN, been around a long time. I can “turn on” my home PC from my Remote Desktop app.
Watch what’s still active with your PC “off” — LAN port lights, external hard drive light...
Thanks for the explanation. We don’t have external hard drives and are not connected to a LAN, but only the Spectrum ISP. My desktop is connected to the modem via ethernet cable. My brother is via wifi.