I've been having this problem too. Googled it and 1 suggestion said this happens to some people after they have done a software update? Solution was to go to settings, wi fi, select the relevant network and use "forget this network". After it removes the info then proceed to re-recognise the network. Apparently it has fixed the problem for some people. Am yet to try it - trying to locate the password/code I need! Let me know if it helps anyone please!