Establishing VPN connectivity

I recently ordered a 256 Kbps internet DSL connection from Airtel. I was provided with a Yuzon Web Distributor II modem (with Ethernet) for connecting to the internet by Airtel. My router was configured by the personnel who came to install the same. The setting of interest was the mode in which the router was configured - "PPPoA routed". I had to provide static IP to my LAN adapter for internet to work on my machine i.e.

I installed a wireless router (NetGear WRG614) after the modem to create a Wi-Fi network at home. Netgear auto configuration is excellent and it was a breeze setting the same up. Contrast this with MN-700 that sucks big time! The crux is that static IP was assigned to my Netgear AP and LAN adapater was configured for automatically getting the IP and DNS.

The internet connectivity worked hunky dory with this configuration. Websites ( reported a 183 kbps (download) / 190 Kbps (upload) on the connection with local LAN speeds at 100 Mbps and wireless connectivity at 11 Mbps.

Enter the MS corpnet. To access internal sites, we need to VPN into the network. Tried doing that but couldn't connect. After contacting a very helpful and responsive support from internal IT teams, I was informed that due to NAT on my router VPN can't be established. In support terminology -
"the reason that you are not able to connect is due to your system not being able to receive VPN packets. You client is sending data requests to the VPN server but your system is not receiving the packets back to your system.
The most common cause for this issue is related to NAT and firewall devices. The logs indicates that you are connecting from behind a NAT device. Please bypass the NAT device by connecting your computer directly to the broadband modem and then attempt to connect again."

Hmm.. Now it was turn of Airtel broadband tech support to help. The Tier 1 support couldn't help with the VPN and then was escalated to Tier 2 technical support at Airtel. I was able to get in touch with them after a few efforts (they operate between 7 AM to 10 PM).

After the initial suggestions of :
  1. Get a USB ADSL Modem
  2. Get a corporate plan for static IP

the support staff started to explore options. Learning: Know what you want and be fearless to suggest options to support staff. That will atleast spur support staff to think..

finally after 1 hour of talking and brainstorming we figured it out. We set the Web Distributor II to "RFC 1483 bridged" mode. that set the modem to "transparent" mode. On the Netgear modem, I set the connection to require login (PPPoE) and provided my credentials (earlier the login credentials were saved on the ethernet modem). configured the LAN adapter to take IP configuration automatically. And vola! the VPN started to work!

This posting is provided "AS IS" with no warranties, and confers no rights.


Abhishek Kant said…
Discovered some more information on VPN and issues around them from (

1. Some forms of VPN like IPsec rely on packet types other than TCP and UDP; these will not work with the router in NAT mode since the router will only forward TCP and UDP packets.
2. However, it appears that, in bridged mode, the router will not allow packets other that TCP, UDP and ICMP to pass through, if you have enabled IP Filter - to protect the router, say.
3. If you wish to run VPN software that uses packet types other than TCP and UDP - in bridged mode, of course - then you can disable the router configuration by http and telnet instead of using IP Filter.
Narayanan said…
This is Narayanan from chennai.Your post was really usefull,but still ive got few doubts to be cleared.Even i tried to establish a vpn connection.I contacted airtel support centre jus lik you,they forwarded my call to the tech dept.They said getting a static IP wont be a problem.They also said if we establish a VPN with another system we wont be able to access the internet anymore...wy is it so??They advised me to use VPN softwares which are much simpler.Can yu suggest me few??

my mail id is
Mail me if possible.I am sure you can help me.


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