Q: Extend my wireless by connecting A.Express to A.Extreme with an ethernet cable

Is the AirPort Extreme now set up and working correctly?

Do you have a recent version of the AirPort Express?

Will you be using your Mac Pro running Mountain Lion for the setup?

Thanks for the info. Apple will practically do everything for you here.

Connect an Ethernet cable from one of the LAN <-> ports on the the AirPort Extreme to the WAN "O" port on the AirPort Express.

Power up the AirPort Express and wait a full minute for it to display a slow, blinking amber light

Click the fan shaped AirPort icon at the top of the Mac's screen and wait a few seconds for a listing of New AirPort Base Station to appear

Just below that, click on the AirPort Express

AirPort Utility will open automatically and take a minute or two to analyze the network, then announce that the Express will be configured to "extend" the wireless network.

Enter a name for the AirPort Express and click Next

Wait another minute or two while AirPort Utility configures the AirPort Express

When you see the Setup Complete message, click Done

You are all set

Bob - can you help me.  I've just set up a 5th gen Airport Extreme to my MAC.  Using all latest updates, Mountain Lion etc.  Everything working ok.  Now I want to connect a 2nd gen Airport Extreme via ethernet so that I can: (a) connect via ethernet another MAC (it's on another floor) and (b) to get better wifi reception for a Mac book pro closeby to that Extreme.  I've used an LAN coonection from the 5th gen to the Wan coonection of the 2nd gen but cannot get Airport utility to recognize it.  Help!!!

Temporarily, turn off the wireless on a laptop

Connect the long Ethernet cable from the 5th Gen AirPort Extreme directly to the laptop

Try to log on to the Internet on the laptop

Report on your results

Thanks for your reply.  I connected a laptop to the 5 gen with the cable as you asked after having turned off the wi-fi.  Connection was found and internet works fine with such a set-up.

Thanks, this confirms that the Ethernet connection is working correctly.

Turn the wireless back on at the laptop.

Suggest that you perform a Factory Default Reset on the 2nd Gen AirPort Extreme, then follow the same steps above substituting the 2nd Gen Extreme in place of the AirPort Express.

Resetting an AirPort Base Station or Time Capsule FAQ

Thanks Bob but still no luck.  I performed the factory reset as you suggested.  When I hook up the 2nd gen Extreme through a LAN to WAN, it's not recognized.  I did try LAN to LAN to see what would happen, it did show up on the Airport utility but there were a number of error messages.  Back to your orginal directions, what else can I try or I'm I doing something wrong?

Thanks for your patience.

Sorry but I do not know what else to suggest for a procedure that works for me time and again with the same components that you have. All I am doing is following the guided setup in AirPort Utility.  Except for entering the name of the Express, AirPort Utility does everything for you.

If you have the time, we'll go carefully step by step to try to find out where things are going wrong.

After you perform the Factory Default Reset, and have let the Express run for a few minutes and have connected the Ethernet cable to the WAN port on the Express.....tell us in detail exactly what you do next, step by step, and what happens after each step.

Instead of a Factory Default Reset, power up the Express and let it run a few minutes. Then, hold in the reset button on the back of the Express for 10 seconds and release. Allow a full minute for the Express to restart, then connect the Ethernet cable to the WAN port on the Express.

Success - I followed your suggestions and performed a factory reset with all power on and connections made.  It then worked.  Thanks again.