Windows VPN Server

Hi all,
I have set a VPN server with the range of Ip’s → .105;
The problem, obviously, is that no computer will connect to the VPN unless the firewall is set to allow all, and i don’t want that.
No specific setting on Network control seem to work, not the VPN IP’s nor the real ones.
The protocol is a PPTP one. Comodo doesn’t like/accept it?
Thanks in advance,