If you look at my previous question, you'll see that I have two IP Addresses (for the remote device), to configuring our VPN Tunnel:
VPN Device Tunnel Endpoint IP Address: 91.151.a.b
Host(s): IP address(es) to be accessed (Public IP address required): 91.151.c.d
During the IPSec configuration, I need to provide our machine's IP address (left) and the remote device (right), but I still have no idea which of above IP addresses, for the remote device, is the right one for configuring IPSec.