How can I get a VPN connection to establish from one machine, to another that is on a domain and behind a pfSense box?

Disclaimer: This is a homework/lab question, but I can't get any assistance from my teachers since they never reply or pickup the phone.

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Here is an overview of the network (all virtual):

Windows Domain:

Domain Controler

• Not sure if the DC might be impacting this somehow...

W10 Client: 1 network card has an address of 172.16.0.3.

• New incoming connection was added for a specific user, enabling "through the internet" option with a pool of IP addresses.

Outside of domain:

Router (pfSense box): 1 network card has an address of 172.16.0.2 that it is using to piggyback from a DC that is OUTSIDE of the domain above. Port forwarding rule in place with the following:

• Protocol: TCP/UDP

• Interface: 172.16.0.2 vNIC

• Destination: 172.16.0.X address

• Destination Port Range: PPTP

• Redirect Target IP: 172.16.0.106

• Redirect Target Port: PPTP

W10 Client: VPN Connection added in Windows Settings with the following options:

• Server Name or Address: 172.16.0.2

• VPN Type: PPTP

• Username/Password: Provided in those fields.

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I've enabled ICMP on the pfSense box just to confirm I can ping from the Router to the W10 station that is in the domain. I also enabled pinging the interface on that router from any source, but I can't get a successful ping from the W10 client OUTSIDE of the domain, to the pfsense router.

Any ideas of what I should check?