VPN Problem ,MT: cntrl message too big | Windows : Error 868

I’m trying to connect to VPN server on MT by windows client, cisco client. Windows shows error 868,
What does this error means ?
Mt log:
pptp info TCP connection established from 90.xxx.xx.xxx
pptp ppp info waiting for call
pptp ppp info terminating …- cntrl message too big
pptp ppp info disconnected