same thing here in chch nz. our Vodafone router decided to do it last week. i thought it was the router as when your within 2 meters of it sometimes it connects. Another option is to forget the network and re-enter the security code. Again this is only a random fix. does my head in , have been using Ethernet cable direct since this. have yet to find a solution , only affects all the laptops. phones , pads etc all fine.