PPTP problem

Hi, I set up a PPTP server on a RB951 with ROS 6.17 and last firmware but when when I try to connnect from a remote host on another isp the client can’t connect.
I opened the 1723 TCP and accepted the GRE protocol in input and for the client I tried to connect both from a routerboard and a windows pc.
I attached a log debug od the server, I can see that there are traffic on 1723 but not for the gre protocol.
pptp.png

SOLVED WITH 6.18