PPTP works by sending a regular PPP session to the peer with the Generic Routing Encapsulation (GRE) protocol. A second session on TCP port 1723 is used to initiate and manage the GRE session. PPTP is difficult to forward past a network firewall because it requires two network sessions. As such, firewalls are unable to let pass this traffic flawlessly, resulting in an inability to connect.
We need install pfsense with 2 interface
Step 1: Enable PPTP Server (VPN > PPTP).Setup as Image
*Redirect incoming PPTP connections to:If check you will redirect to other PPTP Server(Example Window PPTP)
*Use a RADIUS server for authentication:used Account of Radius(AD,FreeRadius...)
Step 2: create Account for access VPN (click tab users)
Step 3:create Rule for VPN Zone access internet
Step 4: connect to PPTP with ip:192.168.20.203 and test connection