Firewall/NAT

Hi all. looking for some assistance.

I have monowall set up and working, but I am having some issues setting up some port forwarding and perhaps problem with static routes.

I have 1 static IP from my ISP, which I have set on the WAN interface.
The LAN interface I have on 192.168.64.x subnet, with .254 os the monowall LAN IP and a windows server as .10 on it's "WAN" interface, crossover cable between the two

on the windows server's LAN interface, I have 192.168.5.10. The windows server provides dhcp, dns, wins and routing/remote access services. VPN works too. I can vpn into the 192.168.5.x subnet from outside with no problem.

The issue I am having is port forwarding any port to either the windows server (such as DNS), or to any other machine on my 192.168.5.x subnet.

From my monowall, I am unable to ping 192.168.5.10, even when I set up a static route for 192.168.5.x with a gateway of 192.168.64.10.

Not sure what I am doing wrong.

I really need several ports forwarded to internal machines.