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macrumors regular
Original poster
Jun 10, 2014
Hello, I have been trying to get an answer for this for months, with no success whatsoever!

I purchased an Airport Extreme to replace the router I had, D-LINK DIR-827. However, when I connected it, I was surprised that it had the IP address from the ISP modem (Zhone). I noticed that the Airport Extreme was in Bridge mode, and when I changed it to 'DHCP and NAT' i got double NAT. When changed to 'DHCP Only' I didn't get a connection at all.

So, what I am dying to know, is why does the D-LINK DIR-827 can provide DHCP, but not the Airport Extreme? The only thing I do with the D-LINK is connect it from the ISP Box (Zhone) to the WAN slot, and it just works. The D-Link gives me a DHCP from to (And I can change it to any value I want.. it's not a static IP, I can just change the range of the DHCP). When I try to do the same in the airport either I can't get online, or I get double NAT! Why is it that the D-Link can do that by itself with no configuration?

I want the Airport Extreme to do the same! The reason for that, is that I connect via ethernet to the ISP box so I get that IP address (the one assigned from the ISP box) for whatever I am connecting, but I can also connect via ethernet to the DLINK and I get another IP address (, for example). If I have the Airport in bridge mode, I can't do that, and it would only serve as an "extension". I don't want that. I want the Airport to give me a different address just like the D-Link does, but not the one from my ISP.

For example:

I connect Computer A via ethernet to ISP box (Zhone).. I get IP address
I connect Computer B to D-Link via ethernet and I get IP address
I connect iPhone A via WiFi to D-Link I get IP address

As you can see, both the ISP box (Zhone) and D-Link have different IP addresses assigned. When I connect the Airport, I can only get the IP addresses from the ISP box (Zhone) (because it is in bridge mode) but I want the Airport to also have its own IP Address:

I connect Computer B to Airport Extreme via ethernet I get IP address (for example)..

When I select 'DHCP and NAT" option in Airport settings, I can select the range (the same way I can do it on D-LINK), and I do get the behavior I want, but then I get the "Double NAT" WARNING! Why?? Why does the D-Link can do it without "Double NAT"?

I have read on the internet, that I need to request my ISP to put their modem (Zhone) on bridge mode, but why does the Dlink work without doing any of that?

Is there anyone here that could explain to me that? What should I do so that I get the same behavior of the D-Link 827 on the Airport Extreme, without any errors or warnings?

Please help me! I have been trying to solve this for more than 6 months! :(


macrumors Penryn
Feb 20, 2009

I think you should go with "what works".

That is to say, since your ISP's modem (DSL, I presume?) is already providing NAT, leave it that way, put the Airport into bridge mode, and just run it that way.

If you set up the AE in bridge mode, do all your wireless devices work as intended?

Again, if that's the case, go with "what works", and enjoy things as they are...

Personal experience:
When I had ATT Uverse installed, I had an Airport Extreme "ready and waiting", already set up in bridge mode.
The install guy got the Uverse residential gateway up-and-running (it's a combined modem/4-port wireless router).
I turned off the wireless functions on the gateway, plugged in the AE, and everything worked from the get-go. Still working fine a couple of years later...


Feb 19, 2008
The Finger Lakes Region
This is because the ISP modem is a modem/router hybrid device. You have to use the "Bridged Mode" since to golden rule in home networking is the closet router to a modem has to do NAT(Network Address Translation). Get a modem that your ISP will allow and stop 'renting' it from your greedy ISP!


macrumors G3
Mar 26, 2013
Elkton, Maryland
When I select 'DHCP and NAT" option in Airport settings, I can select the range (the same way I can do it on D-LINK), and I do get the behavior I want, but then I get the "Double NAT" WARNING! Why?? Why does the D-Link can do it without "Double NAT"?

The D-Link does not have the programmed capacity to throw a double NAT warning though it is performing the same task as the Extreme. You need to either set the modem to bridge mode or add the Extreme to the demilitarized zone on the modem with a static IP in order to properly utilize DHCP & NAT mode on the Extreme.
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