Hello.-
I have the same problem. I used to have different Wireless Networks to connect to, but now is not possible, getting error "your phone can?t connect to the wi-fi network..". Even setting the router as an open network, it is not possible to connect.
Phone can detect Wireless networks and shows the operational conditions of all of them but can not connect !!. Log of router does not present error or information related to the phone connection.
Phone has been reset soft and hard way but no success. I suspect that WP 8.1 upgrade is the reason but is not possible to downgrade to WP 8.
Any help will be welcome. Thanks.