I have a Windows 2003 server behind a linksys WRVS4400N firewall. I have the latest firmware update and it allows GRE packets through on port 1723. I can create a VPN connection just fine to the 2003 server.
However when I try to get any mapped drives, or resolve any hosts, it fails using the remote DNS.
example, to get to the NAS machine, internal users go to \\nas and in this case the only way to get to it is by IP \\192.168.4.20
DNS resolves internally properly, but NSLookup fails when used from the outside. This is happening on all of the VPN clients I have. I have setup more than 30 VPN sites and it is only in the last few weeks that this has started happening. Using LMHosts is not a viable answer.