Buffalo router local loopback comman

http://support.hornington.com/kb/question.php?ID=704

iptables -t nat -A POSTROUTING -s 192.168.11.0/255.255.255.0 -d 192.168.11.0/255.255.255.0 -o br0 -j MASQUERADE

Where 192.168.11.0 change to your local LAN subnet