Please reset the Internet parameters according to the following methods: iPhone Internet parameter setting method (iOS7): Enter the mobile phone menu, select Settings-Cellular Mobile Network-Cellular Mobile Data Network in turn, and enter "cmnet" in the APN of cellular data. There is no need to fill in or change other items, just turn off and restart the mobile phone after the setting is successful.
If the above operations still can't be used normally, it is recommended to shut down and restart the phone first, or don't call customer service to see if there is still traffic if it doesn't work.
It is also possible that the system network settings are wrong, so it is recommended to restore the network settings.
System version BUG problem, it is recommended to upgrade the latest mobile phone system.
There is something wrong with the baseband of Apple's mobile phone. It is recommended to go to a professional after-sales outlet for maintenance.