VPN not connecting in PB20 II

I have one remote PC I’m installing VPN to a Peplink B 20. Keep getting error message when installing “The remote computer could not be established, so the port used for this connection was closed”
I have others that connect and are working fine. Cant figure why this one won’t connect. Any thoughts?

which vpn do you use and get that error?

Thank for responding. PPTP