I have a Zyxel P-661HW-D1 modem/router with several port forwards that works on the WAN interface. I'd like to make them work for the LAN interface as well, like I'm used to.
I updated the firmware to the last version I found (V3.40(AHQ.4) | 07/08/2009) and I activated the nat loopback option from the command line, that should enable the desired behaviour.
The loopback seems to be active after rebooting the router as well, as I can get this response from the CLI:
ras> ip nat loopback
NAT loopback: on
ras>
Still, the port forwards don't work inside the LAN.
E.g. I have a server on 192.168.1.200:5000
that I can't reach by 192.168.1.1:5000
(router's LAN ip) nor by <WAN IP>:5000
.
Such server is only reachable by <WAN IP>:5000
from a machine that is outside the LAN.