U sure u at LTE enable area?? That's weird.. u on stock rom??
Yaya.. using the code can force the decide to use LTE.. just select LTE only

Think before you give this code. This code is used for factory format. It'll remove all files and settings including the internal memory storage. It'll also reinstall the phone firmware.

PS: Once you give this code, there is no way to cancel the operation unless you remove the battery from the phone. So think twice before giving this code.