Problems with an Airport roaming network

Question

I have an Airport Extreme Base Station, 4th Gen and I am trying to extend its wireless network by connecting an Airport Express (802.11n) via Ethernet to the AEBS.  I have followed the directions here very carefully:
http://support.apple.com/kb/HT4260
Everything seems to work correctly, in other words, I get a green light on the AX, Airport Utility says that it has an IP address out of the correct DHCP network being allocated by the AEBS, but when I try to connect to the AX, my MacBook Pro gets a self assigned IP (169.xxx.xxx.xxx).  It seems that I cannot get to the AEBS DHCP server to get an IP assigned to my MBP.  The signal strength indicator in the menu bar has an exclamation point in it.  When I unplug the network cable from the AX, and plug my MBP in, I get an IP address.  If I unplug the AX from power, my MBP connects to the AEBS just fine and gets an IP.  I have tried three different AX's - two 802.11g's and one 802.11n.
Has anyone experienced this and found a solution? 
Thanks,
Greg

Answer 1

OK, thanks. I'm not familiar with your type of service at all, so not sure that I can help.
I cannot add anything more to what you have probably already done. Apple's settings are correct in the support document, but run through the settings below.
It is critically important that you perform a complete power cycle after you have configured the AirPort Expess and Updated the settings.
I assume that the AirPort Extreme is working correctly when the AirPort Express (AX) is not powered up.
Let's check your settings on the AirPort Express using Airport Utility Manual Setup
Click the Wireless tab below the icons. Settings should look like this:
Wireless Mode = Create a wireless network  (Not Extend)
Wireless Network Name = Same name as the AirPort Extreme network
No check mark is needed next Allow this network to be extended
Radio Mode = 802.11n (802.11 b/g compatible) a good choice
Channel = Automatic
Wireless Security = Same setting as the AirPort Extreme
Wireless Passwrod = Same setting as the AirPort Extreme
Confirm Password
Click the Internet icon,then click the Internet Connection tab
Connect Using = Ethernet
Connection Sharing = Off (Bridge Mode)
Update and the Express should have a green light in about 40-45 seconds
Very Important......Power Cycle the entire network
Power off every device on your network....power down order is not important
Wait a minute or two
Start the modem and let it run by itself or a full minute
Start the AirPort Extreme the same way
Start the AirPort Express the same way
Continue starting devices one at time the same way until the network is back up