Why is the Virtual Server or 1:1 NAT configuration correct, but the NAT still cannot work?

Zyxel_Jeff

Background and Scenario:

We have noticed that some users encounter a situation where the Virtual Server or 1:1 NAT configuration is correct, but the NAT still does not work. What could be the possible reason for this issue?

Answer:

The possible reason is usually related to the security policy allowing the traffic from WAN to LAN otherwise the traffic would be blocked by the security policy.

Additionally, please ensure that the NAT traffic can be accepted by the LAN host server, and that the destination directory is accessible via specific TCP/UDP ports.