From the home screen, use two fingers to swipe down the Status bar.
Tap the Settings icon.
Note: If only one finger was used to swipe down the Status bar, swipe down again to access the Quick Settings menu.
Tap Cellular networks.
Tap Preferred network mode.
Tap to select the network mode.
Note: Automatic or LTE/CDMA is the recommended setting.
The 4G connection settings are now changed.