Hi Ahmad syukur
Thank you for asking. Kindly provide the information below so that we could better assist you.
1. Check you network wetting is in 4G priority. Setting>Network & internet>Mobile Network
2. Could the SIM well operate 4G in different phone at the same place?
3. What is your model name, ZB601KL or ZB602KL?
4. What is your current firmware version?
Setting >System>About Phone>Software information>Build Number
If you try to update to the latest version (WW-16.2017.2004.063), does the issue still remain?
5. Could 4G work in "Safe Mode"?
# How to enter and exit "Safe Mode"
Also, please try to reset Network: Setting>System>Reset options>Reset Wi-Fi, mobile & Bluetooth
If the problem remian the same, to avoid any misunderstanding in the conversation, please provide me further information in English. Thank you.