The device labeled as, "Router", is listed among the computers. I would expect a router to be listed in a different section:
My network map.
In this case, under "Network Infrastructure", are a D-Link DIR-655 ("Xtreme N GIGABIT Router"), a Netgear FR-114P ("Residential Gateway"). The latter is actually configured as a print server and switch, but is not a "gateway".
How complex is your WPA2 key? Is there any possibility that you might have a keylogger?
All devices under the "Computer" section are, in fact, computers. Somehow, the "rogues" have the ability to connect to your network.
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum