Did you ever change the DNS on iOS, if yes change it back to it's original (192.168.1.1)
You can do this on your PC too,
1.Go to the Control Panel.
2.Click Network and Internet > Network and Sharing Center > Change adapter settings.
3.Select the connection for which you want to configure Google Public DNS. ...
4.Select the Networking tab. ...
5.Click Advanced and select the DNS tab. ...
6.Click OK.
Windows 7
Hope to help!