OPPO Reno 5G
Selecting network
You can set your phone to select a network automatically or you can select a network manually. If you select a network manually, your phone will lose network connection when the selected network is out of reach.
Slide two fingers downwards starting from the top of the screen.
Press the settings icon.
Press Mobile networks.
Press SIM.
Press Carrier.
If you want to select a network manually, press the indicator next to "Automatically Select" to turn off the function and wait while your phone searches for networks.
If you want to select a network automatically, press the indicator next to "Automatically Select" to turn on the function.
Press the Home key to return to the home screen.