1. Physical Environment: Start by checking if the SIM card is inserted into the correct slot and ensure all cellular antennas are properly installed.

2. APN Settings: Make sure that the APN configuration matches the information provided by your service provider.

3. Check Device Connectivity: Log in to the device's local interface and use the built-in ICMP tool to ping 8.8.8.8 to test connectivity. If it can connect, then check the connectivity between your device (e.g., computer or smartphone) and the router.

4. Check SIM Card: Take out the SIM card and insert it into a phone to see if it can connect to the internet.

5. Restart: Try powering off the router, wait a few seconds, and then reconnect the power to retry the network connection.

6. Factory Reset: Perform a factory reset on the router and then attempt to connect again.