VPN PPTP Problem

Hi, I had working PPTP configured, it worked for a long time without any problems but for few days I’m not able to connect. Windows VPN says to check GRE configuration (I believe it’s ok),in MT logs I can see that “TCP connection estabilished from x.x.x.x” and nothing more.

What can be the cause ? How to debug it ?

Is your IPv4 now NAT’d by your service provider? Is the public IP of your PPTP server a RFC1918, private, IP or a public global unicast IP?