Hi,
When you connect via PPTP all traffic is going to be sent through the tunnel because it's not like an IPsec client where you can define split tunneling on the server side.
I remember there was an option under the windows client OS where you define gateway precedences and so make certain traffic go over the tunnel (not all). But if you succeed enabling split tunneling, is done on the client side (as opposed to the server side on IPsec).
Federico.
