Need help to configure Arduino Yun as a wireless internet router.

I was trying to configure Arduino Yun to use as a wireless internet router. My laptop is connected with arduino through wifi and I am able to ping internet sites from arduino yun. But not able to access from laptop.

Internet is connected in Wired Ethernet port.
Laptop is connected via wifi with arduino.

when I am pinging the any internet site like "google.com" getting "unreachable" error from wifi gateway. Can anyone help me to find out where I am doing wrong?

http://forum.arduino.cc/index.php?topic=192401.msg1655850#msg1655850

Thanks a lot for your reply.

The link is showing internet connectivity is happening only on one subnet 192.168.1.0/24 but my situation is bit different. I have onky one static IP address from ISP (10.10.172.41/25) and Gateway is 10.10.172.1. I configured these ip addresses in my WAN (wired) connection. My IP 10.10.172.41 is dedicated and I can't use any other IP else authentication will not happen.

Now I want to create separate network for my internal LAN (wifi) and using default ip of Arduino Yun 192.168.240.0/24 with DHCP enabled and connect to internet using NAT or any other method so that all of my outgoing request would happen through ip 10.10.172.41 only.