Before completing these steps ensure wi-fi is disabled, then;
- From the home screen, tap Settings
- Tap Mobile or Cellular
- Check Mobile Data is enabled (the switch will show green) and if it isn't, tap the switch to enable it
- Check 4G is enabled (again, the switch will be green) and if not, tap the switch to turn this on
The iPhone 6 and 6 Plus are both 4G capable devices. If the mobile internet connection is 4G rated, the handset will show this next to the signal indicator in the top left-hand corner of the display. 3G, E or GPRS may also be displayed, but these represent a slower connection speed, dependent on location.
If you don't get any internet connection on the device through mobile data, check the devices network settings.