1, restart the phone:

2. Go to Settings-Applications and Permissions/More Settings-Application Management-More-Show System Processes-Find WLAN-Store and try to clear the data cache. (Some models need to go to Settings-More Settings-Applications-All, and find the corresponding software to clear the data cache. )

3. Enter Settings-System Management/More Settings-Backup and Reset/Restore Factory Settings-Restore all settings (data will not be lost when restoring settings).

If the above methods can't be solved, it is recommended to bring your mobile phone to the customer service center for help.