The way to follow

Eventually replace the 10.0.0.x by your addresses

  • Go to Administration -> Diagnostics and click on run
  • Enter
ifconfig vlan1:1 10.0.0.1 netmask 255.255.255.0<br></br>

and click on Save Startup

  • Enter
/usr/sbin/iptables -I POSTROUTING -t nat -o vlan1 -d 10.0.0.0/24 -j MASQUERADE<br></br>

and click on Save Firewall

Source