After using some time trying to get a pptp to a VPN server running Microsoft Windows 2003 R2 i finally found a solution. This article made me aware of a Network Manager pptp plugin, but it seems to have been changed a grate deal since the description in the article (I’m using Jaunty), so I had some problem connecting. In the end I made a connection with a windows computer and used the settings used there, here is the result.
Start by installing network-manager-pptp and restarting Network Manager (/etc/init.d/NetworkManager restart) now create a new VPN profile by left-clicking the Network Manager icon choosing “VPN connection” -> “configure VPN” -> “add” -> “Point-to-Point Tunneling Protocol (PPTP)” -> “create”.
Access point: the ip of the VPN server
User name: User name of the user you want to login with
Password: password of the user
Now (and this is what made the difference for me) choose “Advanced” and make sure only MSCHAPv2 is selected enable “Use Point-to-Point encryption (MPPE)” and choose “Security: 128-bit (most secure)”.
This worked for me, but keep in mind that your VPN server might be set up differently, if you have problems, try connecting from a windows computer (the setup is quite simple) and see the details about the connection and try to match them in NetworkManager.