I've been painstakingly creating a virtual duplicate of our physical Windows 2003 Small Business Server Premium, and I've finally got everything working except the VPN connections. This is despite having restored an exact backup of the ISA 2004 configuration from the physical server (known good) to the virtual server.
When attempting to connect via VPN to the virtual server using a laptop that can connect to the physical server without a problem, the connection times out and a message is displayed saying that the L2TP security could not be negotiated.
Research led me to suspect that Trend Micro Worry-Free Business Security might be the factor, so I tried disabling the Trend Micro Personal Firewall Service, which may have been adding layers of confusion and over-restriction on top of the ISA 2004 firewall. I still could not VPN in at that point (from a machine that VPN's into the physical server without a problem). So, I learned how to uninstall the Personal Firewall component of Trend Micro WFBS.
I will try standing up the virtual server tonight when our users are off the network. Until then, does anyone have any possible suggestions that could improve my chances of success with this VPN?