The recent firmware upgrade for Airport Extreme, 7.5.2, actually breaks DHCP if you have an OS X Snow Leopard server handling DHCP IP address assignments. I found this out recently after running the update and then finding that all my WiFi devices could no longer get an IP address on my network and this was confirmed by others in an Apple discussion forum. Thanks Apple - once again taking a lesson from the Microsoft playbook and how to make things worse. The fix, downgrade to the prior firmware version, is described in this article as is a discussion on what Apple really needs to do with their Airport Extreme.
It appears that Apple is on a streak lately of pushing out upgrades that make their sexy devices fail. Prior to this Airport Extreme mistake, there was the iTunes upgrade that makes it so many folks can no longer sync their iDevices. Now with 7.5.2 for Airport Extreme, Apple has managed to make it so that if you are using an OS X server, in my case running on a MacMini Server edition, the server can no longer automatically assign the IP addresses for ANY of your WiFi devices…in my case this means 4 laptops, 2 iPhones and on iPad.
What Apple also has yet to fix, is the fact that the Airport Extreme has NO SETTING to allow it to be attached to your internet modem yet disable DHCP altogether so that a server can handle the IP addresses. Instead, you still have to have the Airport Extreme hand out your server as its only IP address in its DHCP range so that when no other device can get an address, the server can take over. With 7.5.2, even this no longer works….you have to change all your devices to an assigned IP address from the device itself.
The only good workaround for now is to downgrade your Airport Extreme to version 7.4.2. This still requires that you configure DHCP on your Airport Extreme and assign your server as its only IP address, but now your server will once again be able to hand out addresses again instead of all your devices having a self-assigned IP address that does not connect to your server or the internet.
Here’s how to downgrade your Airport Extreme. Launch Airport Utility from your computer. Hover your mouse over the word Firmware as shown in the settings page to reveal that this is a clickable item. Click on the word Firmware in order to open another window that allows you to choose any prior version of the firmware to install. Then, choose 7.4.2, and let the downgrade begin.
Now, Apple, how about doing what’s right? Enable NAT yet disable DHCP so that those of use who think your WiFi router is otherwise pretty good, doesn’t have to jump through hoops to make it do what LinkSys and DLink do with no fuss? It is very tempting to just solve all these issues by replacing my base station with another brand that has proper settings and just use the Airports that I have as signal repeaters. Servers are supposed to handle DHCP on networks and is one of their major roles in this environment. Apple makes us jump through hoops by not even alllowing this easily and just made things worse with firmware 7.5.2 which, if you have a server delegating your IP addresses, you must avoid. For now, Airport Extreme is a home newbie WiFi router and not useable for the business world.