If an app on your iOS device has suddenly stopped working correctly and relaunching the app didn’t help, clearing the app cache may get things working properly again.
To do this:
1.Please open the “Settings” app on your iOS device.
2. Tap on “General” followed by “Reset”
Choose “Reset Network Settings” and confirm that you wish to clear out all network settings (though not specified, this includes all DNS data) When the device reboots, the DNS cache will be cleared.