Pokemon go: login with 4g impossible [duplicate]

Solution 1:

I had this problem as well

Why is it happening?

At the first launch of the app, a setting must have been selected automatically that restricts data access to the Pokemon go app.

How to fix

Go to:

1. Settings of the phone
2. Go to the apps section of your settings
3. Click on "reset app preferences" in that section, and then launch the app.

Downfalls

This will reset the app preferences for every app, which means that when you launch an app, it will again ask you a prompt for access to a certain feature on your phone. For example, Gallery will ask for permission to your photos the next time you open it.