This can have the following reasons:
- Endian Firewall is behind a NAT device
Endian Firewall is behind another device which does NAT, like a router or another firewall which does not allow connections going through the device directly to the firewall.
You can solve this by configure a port forwarding also on that device to the Endian Firewall's RED ip.
- Server has wrong default gateway
The Server to which the portforwarding should go has configured a wrong or no default gateway. Connections will be directed to the target ip address but since there is a wrong default gateway, packets will not be directed through Endian Firewall.