I have 2 problems with the same issue, and I hope you guys can help.
I have an XP service pack 2 machine as a VPN server. Without the XP firewall and whilst in the DMZ of my router all works as I would expect, file and print sharing, access to the LAN etc.
Switching the firewall on or moving the machine back onto the LAN both stop the VPN from working, and I was hopeing you'd explain why, and how I stop it.
Switching on the Firewall
I get a connection, the machine gets on the network, but only 331 bytes are transfered. I have an IP address, but nothing comes back for things like file sharing (the network icon shows data going up, but nothing received) I have checked the firewall settings on the server and 1723/TCP is enabled on the firewall, PPTP and L2TP are enabled in the advanded options of the firewall for the LAN card, What am I missing? (note file and print sharing are enabled and did work previously)
In the firewall logs I can see that there is quite a bit of dropped traffic to the VPN server IP (not the LAN IP, but the base of the VPN connection pool, this is not the connected IP either) I cannot see the adapter in the firewall configuration, so cannot change this?????
I have seen an article about service pack 2 and negotioation issues, but this fix does not work in either scenario (installed on both machines).
Moving the machine out of the DMZ
I have a DLink DSL-G604T with the latest firmware (PPTP passthrough enabled on the box). I have port 1723 virtual servered to th VPN machine and UPnP enabled on the router. Connecting now, with or without the XP firewall, I don't get past the verifying username/password, then Error 721.
Can anyone please help me with this.