I have an ISP which is using NAT. When I connect my AirPort Extreme, I get a warning for "Double NAT". This is when one IP is distributed. If I choose bridge mode, I don't get this message. BUT, I want to open ports to allow remote access of a NAS disc connected to the AirPort Extreme. How can I achieve this? Shall I use the AirPort Extreme in Bridgemode, or to Distribute one IP, and where shall I open the ports; contact the ISP or just allow them in the AirPort Utility?