Windows remote access server (PPTP) advertised routes

There is no way to push routes from a PPTP server. The connection is established and configured using IPCP, the PPP Internet Protocol Control Protocol defined in RFC 1332. In fact, its very name ("Point to Point") implies that you won't find any support for routing.

Which routes are available depend entirely on the client-side configuration. There are three different ways to configure the client.

1. Use default gateway on remote network. This allows you to access all remote networks, but prevents you from accessing local networks.
2. Class-based route addition. If you aren't using method #1, then most clients will set up a route based on the IP address of the PPTP adapter.
3. For Windows clients, you can use CMAK to configure a connection profile and deploy that to your VPN clients. Essentially you are creating a script to add custom routes when the PPTP connection is open.