Configuration is simple if you start from a factory default condition. Connect the main Airport to AC power and finally to the Internet modem (or modem/router). Open Airport Utility on your Mac or other computer and accept all of the recommendations. After confirming that it works, insert your desired administrative and WiFi passwords.
Then connect the extender to AC power. As before, open Airport Utility on your Mac or other computer and accept all of the recommendations. No need to add password info.
Do not expect the Airport to respond instantly to the configuration commands. BE PATIENT!
I have two Airport Express units (an802.11n and an older 802.11g), and the 802.11n is connected via ethernet to my modem.
And that....unfortunately is the issue here. You need two of the 802.11n versions of the Express to make this work.
The older 802.11"b/g" version of the Express does not support the "Extend a wireless network" feature.
Apple's instructions to do this are in the link below. You will notice that this support document talks about setting up an 802.11n network to "extend". The "Extend a wireless network" setting is not to be found on your older 802.11g Express.
Hi Bob. I was wondering about that. But, I've had these exact two base station set up to extend my Internet reach before, and it worked fine. And for a long time. At one point I decided to increase my security (better encrypterd password) and since then I couldn't get the setup to work properly again...
On the "g" Express, open AirPort Utility and click Manual Setup
Click the Wireless tab below the row of icons
Click the selection for for Wireless Mode
Review the available settings that you see here
Do you see a setting for "Extend a wireless network"?
If you don't, there is no way to configure the Express to do what you want. My guess is that you had the Express configured to "Join a wireless network" previously, but it does not "extend" when it "joins".