From within the Settings app, tap Network & internet.
Tap SIMs.
Tap or slide the Mobile data toggle switch to ON.
You can also adjust your mobile data settings from the Home screen by swiping down from top edge of the screen.
Swipe down to access the quick settings.
Swipe right to left to access the mobile data toggle.
Tap the Mobile data toggle button.
Tap Turn on.
You've completed the steps!
