Make incoming connections on LAN2 use a different gateway.

[KurianOfBorg]

Local interfaces:
LAN1 & LAN2

Default gateway:
WAN

Additional gateway:
LAN2GW (a NAT mode ADSL router on LAN2's subnet).

I'm trying to access pfSense from the Internet using the ADSL router as a backup remote access line. The ADSL router has to be in NAT mode since its used as a gateway for other clients on LAN2 which don't use pfSense as their gateway.

In the ADSL router I have forwarded port 80 to pfSense's LAN2 address. I created the following rule on LAN2:

However it looks like the pfSense web server is still sending response packets through the default gateway WAN instead of LAN2GW.
The port forward only works if I change the default gateway to LAN2GW.
The "statefulness" doesn't seem to apply in this case and thus LAN2GW isn't being used for response packets on the same TCP connection.