APN is a important information when you want to access the cellular internet, we have build-in APN information in the software but the network carrier may change it.
First, open a web browser and go to http://cudy.net or http://192.168.10.1.
For details, please refer to How to log into the web interface of Cudy Router?
Then click General Settings->Cellular->APN.
Note:
1. The Username and Password are optional.
2. You can contact your internet carrier to get the correct APN value and Authentication Type of the SIM card.