If you have WPS enabled on your WiFi router, then somebody most likely got your password. Disabling the pin won’t save you, you have to completely disable WPS. I haven’t see any devices that aren’t mine under Network, since I kicked them off my network, and disabled WPS, and changed the password.
My computer also scans the network every five minutes, I’ll get an email if somebody is on it. I also manually check it.
I wonder if it caches the results, because the first time, I saw devices that weren’t mine, I logged onto my router, and nobody appeared to be on it, that shouldn’t of been.
Could of been a Windows bug. I’ll keep checking my network constantly for an intruder.