How to Check If NAT Feature Failed On Router

Two essential features of a Small Office router is NAT and DHCP feature. NAT (Network Address Translation) feature converts single public IP address from Modem into a number of private IP addresses and helps multiple computers connected to the router to access the Internet. Yesterday one friend called me to check his LAN because only one computer connected to the router was able to access the Internet. The reason for other computers failed to access the Internet was the NAT failure on his Router. NAT feature on his router is no longer working and it is no longer converting Public IP address provided from ISP to private IP addresses. All the computers in the LAN are getting unique IP addresses because of the DHCP feature but no more sharing of Internet connection. It can be tricky for an average user when all the computers are getting a valid private IP address but just one computer is getting Internet access.


As I said before, it is difficult for a person who doesn't know basic networking to find the real reason if all computers are properly connected to the network and getting a proper private IP address. If you are not an expert in networking, just check these two points to find whether Network Address Translation is working. Take your time to check these two facts on your LAN.

1. Only one Device connected to the network can access the Internet
   
   
2. Getting Public IP address on Device which accesses the Internet in LAN
   

In this case, you can verify NAT is not working.


There are some steps to check whether we can recover the Network Address Translation feature back.

1. Ensure that your router is not in bridge mode
   
   
2. Login to setup page and ensure checkbox near NAT is checked
   
   
3. Reset and Reconfigure the router

If still, your router shows Network Address Translation issues, it is the time to replace your router. Having configured modem/router in bridge mode disable NAT feature. In bridge mode, the IP address modem receives a transfer to the computer connected to the modem(with the routing feature) without changing. To configure a modem in PPPoE mode or in bridge mode, follow the instructions provided in the link below.
Configure Linksys WRT54G in PPPoE

To learn more about how Network Address Translation is supported in PPPoE mode, visit the link below.
What Are The Differences Between PPPoE Mode and Bridge Mode

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