Paging Dr. Astaro - L2TP over IPSec Failures

Hi. I am having trouble figuring out the root cause of L2TP over IPSec VPN failures and would appreciate insight from anyone who might know how to resolve this problem.

Scenario -

Internet -> (209.0.141.30) Apple Airport Express (192.168.2.1) -> (192.168.2.5) ASG 8.301 (10.0.4.5) -> (10.0.4.10) HP 24 Port Switch

The ASG is my DHCP server.

The Airport Express is there until I get comfortable understanding and configuring the ASG at which point I will take it out.

The Airport Express also has a Wi-Fi network that I use on occasion for troubleshooting. Now is one of those times.

Issue -

I am not able to get a L2TP over IPSec VPN connection when coming in over the Internet. I am getting errors that I am not sure what to do with (so traffic is passing through the Airport Express just fine, it appears).

However, I can get a good connection - and repeatedly get one - when coming in over the Wi-Fi network (using a iPhone with a 192.168.2.x address). And, it appears to be routing my traffic correctly based on tests that I have done. So, knock on wood, everything there appears to be fine for now.

In the Airport Express, I have a rule set up to forward VPN traffic (UDP ports 500, 1701, and 4500) to the ASG.

I have attached a log file showing both a good connection (coming in from 192.168.2.x) and a bad connection (coming in from the Internet) which shows the errors.

Any help or insight would be appreciated.

Thanks,
Jason

Attached Images

Screen Shot 2012-05-02 at 8.46.45 AM.jpg (60.9 KB)

Attached Files

ASG 8.302 L2TP Over IPSec.txt (11.5 KB)