openvpn

I follow the steps from this to setup my VPN server:
https://wiki.debian.org/OpenVPN

and here:
https://openvpn.net/index.php/open-source/documentation/howto.html

The important for me is:

Next, you must set up a route on the server-side LAN gateway to route the VPN client subnet (10.8.0.0/24) to the OpenVPN server (this is only necessary if the OpenVPN server and the LAN gateway are different machines).

Make sure that you've enabled IP and TUN/TAP forwarding on the OpenVPN server machine.