This is a private home network with a router connecting a laptop and a desktop with a class 7 Ethernet cable. The network functions, it shows my desktop W10P2004DT, the laptop W10H2004LT as well as a phantom computer named DESKTOP-3ANM119. The workgroup is the default WORKGROUP for all.
My concern is security. How can I track down this connection?
Are you seeing the device in Explorer > Network or somewhere else?
Assuming you have a router and can log into it, most of them if not all have a menu to view devices that are connected to your network. I can't tell you what that menu will be as it varies.
If you find the menu it should tell you if the phantom device is connected via WiFi or Ethernet and should also have a way for you to kick the device off.
Since it is unlikely that someone is has managed to connect via ethernet and is camped out in a closet I'm going to guess someone has your wifi password and since the default network name in windows is WORKGROUP it's showing up. But that's just a guess.
I am aware of Windows default naming which was changed and this not a shadow of the old default. This appeared within the past month or so.
What does it show when you open Settings > System > About for Computername.
The issue is resolved. I found and identified the unknown computer on the WiFi network. It was a permitted connection of my elderly next door neighbour, so he can keep in touch with his family, and I completely forgot about it. It never appeared in my network list, because I work mostly late at night using the network and the unknown computer was off.
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