[Nebula] I cannot access my internal server. What steps should I take to check for NAT issues?

Zyxel_Cooldia

Question:
On Nebula, I have configured my NAT ports correctly, but I am unable to access my server using the public IP.
What steps should I take to ensure visibility of my server with the public IP?

Answer:

If you've configured NAT ports correctly but still cannot access your server using the public IP, here are some steps you can take to troubleshoot and resolve the issue:

1. Verify Port Forwarding Configuration: Double-check your NAT port forwarding configuration on Nebula to ensure that it is correctly configured to forward incoming traffic on the specified port to the internal IP address of your server.
2. Test Internal Connectivity: Verify that you can access the server internally using its internal IP address. This ensures that the server is reachable and the service is running properly.
3. Test with Different Ports: If possible, try accessing your server using a different port to see if the issue is specific to the port you're trying to use. This can help identify if the problem is related to the port itself or the overall configuration.
4. Review Server Application Settings: Ensure that the server application itself is configured to listen on the correct network interface and port. Some applications may need specific configuration changes to bind to the correct IP address or port.

You may follow this link to review corresponding NAT rule(Virtual server) on Nebula.

https://community.zyxel.com/en/discussion/14227/atp-flex-how-to-configure-a-nat-rule-virtual-server-on-nebula

Assume the firewall is behind an NAT router, please follow link before to verify your settings.

https://community.zyxel.com/en/discussion/20652/atp-flex-how-to-configure-a-nat-rule-on-nebula-if-the-firewall-is-behind-nat