Wifi Scan

When performing a wifi scan via Avast. It picked up a device on my network and reflected it as NAS (Microsoft).

Is it possible that my PC was routing traffic to a NAS as other people had physical access to this pc. Upon discovering this I installed new version of windows and it removed my old installation of Avast. I did a copy of the old version of all my files etc to a external drive in case I need to recover certain items.

Is there any one here with experience to assist in how I can determine whether or not my PC was breached as my new installation of Avast doesnt show the logs of old system.