If the automatic network selection was deactivated on the Huawei smartphone because another network was searched for manually, it can be reactivated afterwards, in which case we are dialed back into the standard mobile network of our provider.

Android 10 | EMUI 10.0
Step 1:  Open the  Settings
Step 2:  Tap on  Mobile network
Step 3:  Tap on  Mobile data
Step 4:  Tap on  Carrier
Step 5:  Tap on  OK
Step 6:  Enable  Automatic network selection
  1. Open the Settings
  2. Tap on Mobile network
  3. Tap on Mobile data
  4. Tap on Carrier
  5. Tap on OK
  6. Enable Automatic network selection

Huawei Instructions