This issue sounds like what I am experiencing. For the past 2 months the modem will disconnect intermittently and everyone looses signal. Our home is almost completely wireless say I wired computer in my son's room. At first I thought I may be a wifi bandwidth issue as we have 25Mbs and we have 2 laptops, 3 smartphones, 1 iPad, a Wii U and regular Wii. But the SSID is not in the list, but 2 minutes later it reconnects.
Any help would be greatly appreciated!