I have been working out of the house for years for a large corporation. I have had no prior problems connecting to VPN. Recently Comcast disabled the VPN connection through residential accounts and I had to close my cable Internet access and open a separate business account. Two different modems have been brought out, one with a static IP and the other dynamic. When I connect with either of these directly to my laptop, I can get into the VPN, but when I go through a router, (both my old one and a new one I just got), the VPN does not work. I have gone through my company IT, Comcast's IT and Linksys. No one can figure it out. Any suggestions?
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You've done a great job of locating where the problem is. It's probably in the router configuration. Unfortunately without knowledge of what VPN solution your company provides it's difficult to pinpoint exactly what needs to change. Oftentimes (as is the case with my corporate employer), the VPN solution does not handle NAT'd addresses very well to establish the connections. I would need to understand how your router is set up to help you figure this out.
The most common problems with the router configuration for home office is the built-in firewall or non-transparent addressing capabilities. I would check to make sure that the firewall is not blocking the connections and also ensure that it handles transparent addressing. This greatly depends on the router, its capabilities, and platform as to what it does and does not support.
View our wireless expert's response to this question: Problem connecting to virtual private network (VPN) through Linksys router
This was first published in October 2008