1. It may be that the signal coverage of your location is poor. I suggest you restart your phone or try another location.

2. Connect the mobile phone to the wireless network and update the device to the latest version. Note: Please back up the data in the device (such as contacts, information, pictures, etc.). ) Before upgrading.

3. If it doesn't work, please turn off the phone, take out the SIM card and try to insert it again.

4. Replace other SIM cards.

5. If the signal is still unstable, please back up the data (contacts, information, etc. ) and try to restore the factory settings.

If the problem still exists after the above operation, it is recommended that you bring the purchase invoice, three-guarantee certificate and mobile phone to the local Samsung service center for inspection by engineers.