New Device Connected, the router itself?

I tried to search for this and couldn't find any information. When I first setup my modem yesterday and then in the middle of the night I got a notification about a new device being connected that seemed a little weird.

That device was Technicolor CGM4140COM. The MAC address is extremely similar to my WiFi network, only off by a single digit. Obviously no one in my family is connecting with this device.

Is this normal? Why is the router itself (or something in Comcast's control) connecting to my WiFi network? It seems to disconnect super fast as well.