IPsec using public IP addresses

[pico]

Hi,

I have to connect a VPN to another VPN, at a network I dont control, that only allow public (WAN) IP addresses.
Please look at my network setup below:

Lan Server1 –------ Router and VPN Gateway1 -------- |internet| -------- VPN Gateway2

I have control over (Lan Server1) and (VPN Gateway1)
The other gateway (VPN Gateway2) I have to connecto to using public IP addresses, I dont know why, but that is what I am told.

Lan Server1 has the following IP address
192.168.1.45 (LAN)
87.145.245.151 (This is a public WAN addresses NAT'ed using 1:1 NAT to this server)

VPN Gateway1 has teh following IP address
87.145.245.150

This is what the owner of VPN Gateway2 has told me:
Clients must use public IP addresses or be NAT'ed to a public IP address.

I have successfully created an IPsec VPN tunnel between two pfSense gateways, but only using the LAN address, I have never tried setting it up using WAS addresses.

I tested between two pfSense IPsec gateways by setting 87.145.245.151 as local subnet on the local gateway and as remote subnet on the other. In the Status: IPsec I see a connection with a green arrow, but I can not get any connection of any kind between the two networks.

I do not know if I am doing it right or if this even makes sense, so any help would be appreciated.

[pico]

Nobody knows if it is possible to connect two servers with NAT'ed WAN addresses ?