Re: i know wi fi password but can't connect on mobile
Make sure your channel settings are correct if your router is broadcasting on a certain channel and your device is not receiving on that channel it wont connect. I'd recommend setting the WiFi channels to either 1, 6, 12 as these are the ones that are far less likely to run into distortion.
Also make sure your within range of the WiFi router, if your too far away you wont connect.
Also you could try a soft reset of your phone (Vol down and power buttons together for 10 seconds until the vibrate boot up).