I'm sorry to say that I can confirm the same problem (disconnect
after 2 minutes) on m0n0 with Firmware 1.1, 1.2b5, 1.2b6, 1.2b7.
I think I've seen some MTU related problems around this. In /var/etc/
mpd-vpn/mpd.conf I found "set link mtu 1460". This maybe causes some
problems with Windows PPTP, since Windows sets its MTU to 1444 (?).
Maybe the "set link mtu 1460" can be just left out? Where does it
need to be changed?