Solution:
1, open the settings on the phone.
2. Find "Cellular Mobile Network" in the setting interface, and click Enter.
3. After entering this interface, find "Application using WLAN and cellular mobile" and click Enter.
4. After entering, you can see all the apps installed in your mobile phone, then find the app for which you want to set permissions, and click Enter.
5. Finally, select the permissions you want to grant to this application. There are three types: off, WLAN, WLAN and cellular mobile data. Click either of the latter two.