I had a long time problem with my client's CISCO VPN connections to the Australian Tax Office - via HandiTax and Simplefund.

Every time they were lodging to the ATO, they had to retry the lodgement several times before it successfully connected and transmitted.

The problem was consistent across two different software applications but there was a common component with the CISCO VPN client. After the light bulb light up above my head, I googled "Linksys WAG325N CISCO VPN problem" and came across the following forum post on the Linksys site:

http://forums.linksysbycisco.com/linksys/board/message?message.uid=113940

I double checked that the IPSec Passthrough was enabled, but the other part that I needed to add to the router configuration was to put entries under Applications & Gaming -> Port Range Triggering. I did another google search for which ports are used by the CISCO VPN, and put in 500, 4500 and 10000.

Here is a screenshot (click it for a larger view) of the relevant page on the router setup.

After I made these changes, lodging returns to the ATO in both HandiTax and Simplefund worked flawlessly each time on first attempt!