I checked again, used same/standard setup as you describe. I reseted my RUT955 to default and did it al over agian...: no PPTP connection... :-((
I tested 2 different clients (win10 & android) which is working fine on an other router (other brand/type) and no problems in setting it all up... Also used Win10 as standard PPTP client, no connection to my RUT955.
Where can I get the best debug info on the RUT955 to see where the incomming PPTP connection is dropped? If I check the events log / network event on the RUT955 I don't see anything concerning the PPTP connection.
RUT955 is directly exposed with public IP, no further firewall or anything in between to the client.
Please advice, thx!