No 4g voice in Prefered Network mode

Hi guys
I have a Huawei p8 lite single SIM.
I want to active 4g network but when I click on Prefered Network mode there isn't the selection "4G" but just these two voices:
- WCDMA/GSM auto
- GSM only

Do you know why?
informations about my model smartphone follow:
Model Number ALE-L21
Build Number ALI-L21C02B130
Baseband version 22.126.09.00.00
Kernel version 3.10.61-g687af2e

Thank you