I've found a strange hostname in my dhcpd.leases file and I'm wondering what steps I should take in response.
I have a simple home network: my modem is plugged into a router running OpenBSD 6.0, and a laptop and an old Netgear router in WAP mode are connected to the router. (The router also has a wireless networking card that's been in host mode with a WPA key set and no physical antennas attached, so it should have been both secure and effectively invisible.)
Within the last 24 hours, I noticed my WAP behaving strangely. It's broadcasting on the 2.4 GHz and 5 GHz bands (both password protected), and while I could log in as usual using the 2.4 GHz SSID, the 5 GHz SSID was consistently rejecting my correctly entered password. I physically powered off my WAP and turned it back on, and everything started working normally again. I started poking around my router, though, and discovered something odd in /var/db/dhcpd.leases. There was a lease listed for an unfamiliar hostname, granted a couple of days ago. The hostname was human-readable and non-googleable -- something like "DESKTOP-F00BAR." The MAC address indicates that it's an Asus machine, and I don't have any Asus devices running in my home.
To my naive eyes, it looks like I've suffered a wireless network intrusion, albeit a benign-seeming one, but I have no idea how it could have happened or what to do next. I've searched my logs but haven't found anything relevant. What's the proper course of action in this situation? Is it possible that my Netgear device is on the fritz and somehow left the network open for some period of time? Is there some other obvious potential vulnerability that I'm overlooking? I apologize for the vagueness of this question, but it seems like I should do something, but I really don't know how to proceed.