The troubleshooting will be to look at the mobile WiFi device’s manual, or a sticker will which will be on the unit somewhere, with the required password.
You will need that password to log onto a web portal for the device, in order to change the APN (Access Port Name) within the device to access the internet through the mobile WiFi device.
If you have any issues with the above, you would need to contact the manufacturer of your device. Their contact number will be available in the manual or via a Google search.
