The configuration of the VPN-service was done strictly "by the book". Literally i followed the "How to"-pdf from D-link and it used to work.
This is what the system log on the Mac says about the event.
Apr 5 09:08:05 sfadm001 pppd[5773]: pppd 2.4.2 (Apple version 560.13) started by carlos, uid 502
Apr 5 09:08:09 sfadm001 pppd[5773]: PPTP connecting to server '212.116.67.210' (212.116.67.210)...
Apr 5 09:08:09 sfadm001 pppd[5773]: PPTP connection established.
Apr 5 09:08:09 sfadm001 pppd[5773]: Connect: ppp0 <--> socket[34:17]
Apr 5 09:08:40 sfadm001 pppd[5773]: PPTP received unexpected message type = 6699
Apr 5 09:08:40 sfadm001 pppd[5773]: LCP: timeout sending Config-Requests
Apr 5 09:08:40 sfadm001 pppd[5773]: Connection terminated.
Apr 5 09:08:40 sfadm001 pppd[5773]: PPTP disconnecting...
Apr 5 09:08:40 sfadm001 pppd[5773]: PPTP disconnected