Different MAC address

I just recently added a homegroup in my laptop to connect to my DCP3941 Gateway.  I am running windows 8. When i check the network settings in my laptop, it added a Network Infrastructure.  When i click on the properties of this infrastructure, it displays the manufacturer which is DCP3941, however, the MAC address of this device is different than the one display on the actual physical gateway that i swapped out at one of the Xfinity stores.  It also displays the UUID which contains the same mac address numbers, which are NOT the same of the actual gateway.  NOW, for some odd reason, this infrastructure, which also displays a connected  mobile device that it is not connected to my actual gateway, dissappeared from the network settings folder in my laptop.  I need someone to help me figure out if someone is remotely connected to my network.