Quite often in towns etc WiFi is cluttered, if you have a Android phone you can download a WiFi scanner (not seen a good obe for mac etc), it will show you who is who and where they are transmitting, WiFi has channels 1 - 11 but the only "pure" channels are 1,6 and 11, the others share radio space with the three main ones, the scanner may show your WiFi on the same channel as many others, if you log into your router you can change from auto to a fixed channel, select one away from other strong signals if poss, if you have no scanner then try random channels like 1, 6 or 11, new routers like the BT homehub also have 5Ghz, it can be set to transmit on its own 5Ghz channel for your devices, then you have say "mywifi" on 2.5Ghz and "mywifi 5ghz" as less people have 5Ghz routers it can be better for your device, the point of my post is that most WiFi problems are from cluttered radio space, if you wonder why some devices work and others dont its often as the data being sent to each is sometimes recieved better on one than it is on another, radio is funny and reacts in strange ways, walls and other electrical devices play havoc with it so often there is no patturn, its an excelent move to try the WiFi scanner and see who is transmitting what, you'll be shocked to see how busy it can be in town etc.
Arthur
