Login as admin and go to 'Configure> Static Route'
Enter your static route in the following format and click 'Save'. For multiple routes, separate each route by a new line.
add -host [host] gw [gateway] dev eth0
add -net [network] netmask [netmask] gw [gateway] dev eth0
Example: add -host 192.168.3.11 netmask 255.255.255.0 gw 192.168.3.1 dev eth0
where 192.168.3.1 is the destination IP , 255.255.255.0 is the netmask and 192.168.3.1 is the gateway
dev should always be set as eth0
For the new static route to take effect, reboot the appliance via 'Configure>System and Modem'