When traveling with my Android phone in a country where I have no mobile data access (because the phone physically cannot connect to the country's frequency bands), my Duo mobile codes for third-party sites like github.com and paypal.com are getting rejected. This is never a problem at home (in Europe) where there is always a mobile data connection. In the "problems" page on the app, it shows all green--no problems detected. These sites do not use push notifications, and I have the Duo app in the foreground so there couldn't be an Android background restriction involved. This is making things really difficult for me, so any suggestions would be much appreciated!