Thanks. Deleting and reinstalling the app usually resolves most issues. If it does not, please reply back with the exact error message. Include a screen shot, if possible.
Do you see "VPN" at the top left of your screen next to the Wifi or LTE indicator? If yes, your device is configured to use a VPN.
If not, do you know if the router you're connected to is using a VPN? Because that would cause the same issue.