N66u to BT Homehub 3 with VPN access

Evening guys,

I am not too great with networking but with Google and some common sense, have been able to muddle my way through... till now! Hoping someone can help.

I want to access my home media server (HP N40l,WSE2012) remotely via VPN. For this I need a static IP.

I have had my N66u for about a year now, working fine as follows:
I am using my BT Homehub 3 as a modem. A network cable runs from its gige ethernet port to the input on my N66u. From there I have gigE out to a switch and from there to PC/Server/Laptop.

DHCP is off and the homehub has a static IP of 192.168.1.14. It's Gateway IP is 192.168.1.254.

The N66u has a WAN IP of 192.168.1.14, subnet of 255.255.255.0, gateway of 192.168.1.254 and a LAN IP of 192.168.2.1. It is using BT's DNS servers. DHCP is ON.

I want to use DDNS on the N66u to set up my static IP. If I click on this, I get the multiple NAT error message. If I switch off NAT on the N66u, it does not help. I cannot seem to switch off NAT on the BT hub.

I cannot put the WAN(BT hub) and LAN (N66u) IPs on the same range without an error on the Asus... Therefore I cannot put my WAN (BT hub) and DHCP (N66u) on the same range without being told it is an invalid IP address.

Any ideas on how to avoid double natting with my setup?