Airport express setup with AirPort Extreme to extend wifi. I cannot get express to setup as wireless even when connecting it to extreme via Ethernet cable. Any suggestions or help appreciated

What have you tried so far to get this to work? I'm asking only because I don't want to offer suggestions on things that you have already tried and weren't successful with.

Airport express setup with AirPort Extreme to extend wifi. I cannot get express to setup as wireless even when connecting it to extreme via Ethernet cable. Any suggestions or help appreciated

We know that things must seem obvious to you there.....but we are severely handicapped here. For example.....we cannot see your network.....and we don't know.....

Which AirPort Extreme model you have (there are at least 10)

Which AirPort Express model you have (there are 4)

What operating system you are using on your Mac or PC (there are many different ones)

The tips and tricks are different depending on which versions of products you have and which operating systems you might be using, so in order to even begin the troubleshooting process, we need some basic information from you, please.

Based on your response, there will likely be more questions that we need to ask before we can begin to suggest a "fix"......so you will need to be patient.....these things take time.

Ok, thanks for the additional information. I am going to assume that both of your AirPort base stations are, at least, 802.11n models ... and that you are using an iOS device to do the base station administration. Are both of these correct?

If so I would suggest that you start by performing a "factory default" reset on the Express. Once completed, temporarily bring the Express to the same room as the Extreme. Do not connect them together by Ethernet.

Your iOS device should now "see" a new Wi-Fi network with a network name of something like: Apple Network NNNNNN. It will be unsecured so use Settings > Wi-Fi to connect to it. Once connected run the AirPort Utility app. Choose the options to wirelessly extend the existing Wi-Fi network provided by the Extreme. Allow the base station to restart. Post back your results.

We don't need the model numbers since you provided the Generation numbers.

But, I'm not clear on "how" you want to use the Express to extend since there two different ways that it can be configured to "extend".

Method One.....highly recommended.....would have the Express connected back to the Extreme using a permanent, wired Ethernet cable connection. This provides by far the best performance and is by far the most reliable way to "extend".

Method Two....uses a wireless connection between the Express and the Extreme. The Express has to be located where it can receive a really strong wireless signal from the AirPort Extreme for this to work. Even if it does, when you extend using wireless, you will lose about about half of the potential speed on the entire network. So, your network has better "range", but speed of the network will slow.

Not sure which way to want to go. Please advise.

Since you are using Yosemite, you need to be aware that there are a number of networking bugs in the operating system that can cause issues when you try to set up a new AirPort. "Unexpected Error" is one that we see all the time.

We can try to work around the bugs, but if you have an iPhone or iPad handy, that can work as well.....and usually, much better..... to set up the Express.

Let us know when you want to proceed.

Sure, after you reset the Express back to factory default settings......leave it "on".

Power off the AirPort Extreme for a minute, then power it back up.

Do not connect an Ethernet cable to the Expess at all. Setup will be over wireless.

On the home screen for the iPhone or iPad.....

Tap Settings (gear icon)

Tap WiFi

Look for a listing of Setup AirPort Base Station

Tap on AirPort Express

Follow the prompts