Airport extreme (5th gen) and netgear router (DG834N) cannot set DHCP and NAT

I currently use the Netgear to connect to ISP. I set the LAN side address to 10.0.1.1. My airport extreme is set to connect as "Connect to" internet is set to Static and the adress is 10.0.1.2. The extreme allocates addresses from 10.0.1.3 onwards. I want to connect to the LAN from the Internet. The Internet options are set to Configure IPv6 automatic and IPv6 to tunnel. When I try to set the Router mode to DHCP and NAT I get the error message

"The DHCP range you have entered conflicts with the WAN IP address of your base station"

I cannot use the Airport to connect directly to the ISP as they use PPPoA not PPPoE. The address the ISP provide is a static address.

Can anyone help?