Problem:

After a 2G/3G SIM card is installed on the phone, the 4G signal icon is displayed repeatedly and the phone disconnects from the 4G network.

Cause:

If 4G network is available in your local area but 4G services are not enabled on your phone, the phone will attempt to register with the 4G network because it is given higher priority. When the network detects that your phone hasn't enabled 4G services, the network access is rejected, resulting in your phone repeatedly displaying the 4G signal icon and disconnecting from the network.

Solution:

1. It is recommended that you use a 4G SIM card to access the Internet.
2. Swipe down from the screen to show the shortcut menu, touch and hold Mobile data to access the settings screen, then disable Enable 4G or set Network mode to 3G/2G auto.
   

   If Enable 4G or Network mode is not displayed, it indicates that 4G is enabled on your phone by default.

More knowledge:

The phone has an unstable signal