1. If the signal is weak in a remote or closed location, you can change the location and go online for testing;
2. The Internet access function of the mobile phone is disabled, and the number has been stopped. You need to restore the normal status of the number before you can access the Internet;
3. Check the settings of the mobile phone, such as whether the mobile phone data is turned on and whether the flight mode is turned off.
4. Check whether the mobile phone card is damaged or not inserted correctly. It is recommended to change the mobile phone for testing.