Share PPTP Connection to local network computers

The settings you're looking to change are client-side only, unfortunately. Unlike, say, OpenVPN, where you "push" configuration information from the VPN server to the client, in the Microsoft VPN client the "Use default gateway on remote network" option is set client-side only.

The Connection Manager Administation Kit (CMAK) will let you build an EXE that can be run on clients to setup the VPN connection with all the parameters you want.

Some frustration may come from the unfortunate method by which the client receives a route to the remote network. When the "Use default gateway on remote network" option is disabled, the client receives a route to the remote network based on the "classful" IP address of the VPN server (this changes in Windows 7, but I don't have details of the change handy). If you're just doing a VPN into a little "/24" network numbered "192.168.x.x", then this will work out fine.

If you have a more complex topology, though, this will give you fits. The CMAK is supposed to give you a way to run a script on the client after the VPN comes up, and to modify the client's routing table, but I've never actually gotten that functionality to work on Windows XP SP2-based client computers. I'd love to hear from somebody who has.

I guess I shouldn't just leave this unanswered forever when I have in fact solved the problem.

When I was hired, I was told that the LAN was "running out of scope". The network had a 24-bit subnet mask and uses DHCP for client addressing. The DHCP server wasn't set to check DNS before handing out addresses. DNS wasn't set to scavenge old records. RRAS was set to get addresses for VPN clients from DHCP, and by default it grabs blocks of 10. So it would grab blocks of 10 and start handing them out to clients, but as our address space ran out, some of them were "good" and some were already registered to other clients in DNS. I shortened the subnet mask to 22-bit and the problem was solved.