I have a DSL-N12E Asus router (dsl uplink + router + wifi AP) at house, and on average 5-10 devices which connects to it with WiFi. Frequently different devices reports they lost wifi connection - sometimes they reconnect seamlessly, sometimes one have to click "connect". Always there's no problem with reconnecting (except sometimes you have to do it manually).
Yesterday I had 3 laptops on my desk (one with linux/debian, one with windows 7 and one with windows 8.1) and I noticed they all disconnect at the same moment. The router has some system log, but nothing there and I didn't find an option to enable some extra logging (maybe I missed something).
I can't think of any interference from the environment - I have no microwave and I live in the country with only 2 houses in the neighbourhood, can't see any wifi devices announcing, except 4 other wireless devices (link to the family house, and AP there) which are on different channels (asus in on channel 11, the others on channel 8 and 3).
Any idea how to diagnose it, or what to change to fix the problem?