Are you plugging your workstation directly into the LAN port or are
you using a switch.

--> intet-->m0n0-->sw--> pc

Also, I'd try setting your PC to DHCP...Let the pc get it's IP scheme
from the router/firewall.If you must, try setting m0n0wal up again
with DHCP enabled from , say 192.168.3.100- 192.168.3.150 with DHCP
enabled. Reboot the router than reboot your PC. If your pc is windows,
do ipconfig /all and see if your nic is properly assigned. If
Linux/BSD, type ifconfig ... same results.

If your pc say IP: 169.X.X.X, then it's not getting an assignment from
the router. Check to make sureyou have the right cabling.

Don