|I've never setup a VPN server on windows, but I have run into that type of an issue before. |
Normally it's because when IPSec gets enabled on the interface, it will not pass unencrypted traffic unless you setup a policy to do so - so i.e., your internet traffic is blocked because you're not communicating w/ a secured peer.
Verify the "Enable security on the selected interface by setting up static packet filters" is DISABLED in your config, or try setting up some kind of IPSec policy to pass the unencrypted traffic (no idea how to do that in RAS, sorry)
Try this page: