What is this Double NAT error I have? Is that why can't connect to Apple TV

As I replied to comTee, what it means is that your Earthlink provided "box" must be both an ADSL modem and a router combination and you have two routers back to back. It seems to me that the firmware change now reports this in an effort to be helpful, detecting situations where users may have inadvertently connected two router back to back. You have to decide how to proceed. Easiest is to let the AEBS(n) be a bridge and leave your Earthlink provide box as is. Otherwise, convert the Earthlink box to bridge mode and use the AEBS(n) as your firewall. Given the performance problems noted elsewhere with AEBS(n) and NAT, I would consider the former.

In my own home network, I use a WatchGuard firewall to connect to my cable modem, then a bridged AEBS behind that.
Similarly at my office where the mating WatchGuard firewall router lives, a bridged wireless access point sits behind that.

I am also having this same problem after updating the firmware to 7.1.

However, my 8 year old Earthlink supplied DSL modem is not a router, as I understand it (only a single ethernet connection). That is why I got the new AEBS.

While I can switch to bridging mode and get the AEBS to go from flashing amber to green (and thus restore my network, which includes 2 AExpresses for wireless iTunes only), I now no longer can share my single IP address internet connection with my wired G4. This is what I need, without jumping through hoops.

This was working fine before the firmware update, simply doing the auto-setup for the AEBS right out of the box. Autosetup now gives me the double NAT error (as well as a manual setup).

Not sure why this has suddenly become complicated when all was fine before.

Brian

MacBook Pro Mac OS X (10.4.9)

Bridge Mode is NOT an option, especially since it was acting fine BEFORE the update

i have 2 networks, a 192. network ( another room ) and a 10. network going through another router. The AirportExtreme N was working fine in this configuration. a Router just routes information from 1 range to another, it Should not matter what range is comming from the internet port, that is left to whatever is on the other side

So, if you know that your installation is OK, then just check the box to Ignore this specific error condition and you should get a Green LED. I assume you have Internet connectivity but are annoyed by the LED not being green; this should fix it. Bridge mode is an appropriate solution for the previous situation, but perhaps not for yours.

There are some network protocols that do not work through a double NAT, so the AirPort now alerts people to the problem in case they have issues.

Double NAT mostly works, but it is a good thing to avoid.

i havent checked the ignore as no idea how to uncheck it if it doesnt work, i was assuming the green light is just informational, not limiting ( aka it could flash amber all day and not effect the actually connection status )

I'm using Airport Extreme with a Bellsouth DSL cable modem which is configured as a DHCP server. I also get the Double NAT error but checked the ignore box. I have not enabled Bridge mode on the AEBS (using Shared IP Address) and my network has been working fine with one exception -- my single Airport Express is now invisible to the network. iTunes can't see it and neither can Airport Disk Utility. I'm not sure what the best solution would be:

Reconfigure the cable modem to Bridge Mode and use AEBS for DHCP;

Reconfigure AEBS to bridge mode;

Something else...?

The reason I'm not clear is that the Airport Express box became invisible before I updated the firmware on the AEBS and before I experienced the Double NAT error. Everything else on my network seems fine. I don't get why the AEBS should have interfered with the Airport Express box in the first place -- it seems like these two devices ought to be fully compatible with minimal effort.

iTunes can't see it and neither can Airport Disk Utility.

It makes perfect sense that the AirPort Disk Utility can't see the AirPort Express (AX). The AX does not support any disk drives so there is no need for the AirPort Disk Utility to see the AX.

Have you tried connecting your Mac directly via Ethernet to the AX and configuring it?

I meant to say that Airport Utility couldn't see the express box.

It's all good, now, though. I just reset the AEX to factory default settings and Airport Utility saw it and I was able to configure it. I'm now running green on both devices (I set the AEBS to Bridge mode).

Thanks.

Technorganix,

Does bridge-mode has any effects on programs using NAT and will the AEBS firewall be inactive after that?

i was assuming the green light is just informational, not limiting ( aka it could flash amber all day and not effect the actually connection status )

Correct.