Quick video walkthrough:
If you prefer to read, or have a slow connection following this guide:
Manual selection availability depends on your Peplink model, and the firmware you are running.
If you would like to choose a different on your Peplink router:
Login to the Peplink admin console.
Go to the details of the cellular module
Next to Carrier selection, click the question mark (?) where it reads auto
Select Manual
Perform a scan and choose the required network