Replacing an AirExtreme

Scratching my head. Setting up the AirPort Express to join a WiFi network is as simple as setting up a new computer or iPhone / iPad to join a wireless network. You select the name of the network to be joined and enter the password for the network. The only thing different here with the Express is that you are also assigning a device name to the Express.

After you see the "unexpected error message" appear, close AirPort Utility and try connecting your Mac back to your router's WiFi network. Then open AirPort Utility again to see if the Express might have joined the network.

Sorry, I am unable to duplicate the error or error messages that you are seeing. The screenshot that I posted before for the network named "2Wire902" is for a 3rd party WiFi router that my next door neighbor is using. I have the WiFi password for the network because I help out on computer related stuff with the neighbor. The Express joins the network with no problems.

To eliminate the possibility of an issue with your Mac, try setting up the Express using an iPhone or iPad.

Go to the Home Screen on the iPhone / iPad

Tap on Settings

Tap on WiFi

Tap on AirPort Express under the listing of Set Up New AIrPort Base Station

If you are still having problems, one possibility might be that your new router is using newer types of WiFi security that the Express is not capable of using. Remember, even the most recent version of the Express was designed in 2012 with technology that was available at that time, and Apple never updated the product for newer versions of security.

It also might be possible to set up the Express to connect to your router using Ethernet and not use the WiFi on the Express at all. But, this would require that the Express remain permanently connected to your router using the wired Ethernet cable connection. Post back if that is a possibility for you to consider.

If all else fails, you could try an AppleTV to join the WiFi network, but your amplifier or speakers will need to have an HDMI input, since the only output on the Apple TV is HDMI. The AppleTV will join networks of newer routers that are providing new security settings.

If you performed a Factory Default Reset, the network settings were erased, as well as as previous profiles. Recommended.

If you performed a Hard Reset, the network settings were erased, but a record of the previous profile is preserved. There would be no reason to preserve the previous settings that worked with your AirPort Extreme, but you can do so if you wish.

After you have performed a Factory Default Reset or a Hard Reset, you need to reconfigure the AirPort Express again to join your current network, just like you did when you originally set up the AirPort Express.

Click the WiFi menu at at the top of your Mac's screen

Look for a listing of New AirPort Base Station

Click directly on AirPort Express

When you click on AirPort Express, that will start up the AirPort Utility setup "wizard". The wizard will take a few seconds to analyze the network and then display a screen that looks like the example below, except that you will see the name of your router's WiFi network displayed.

IF.....there are other WiFi networks nearby, you may be asked to select the specific network that you want to use with the AirPort Express

Base Station Name......Type in a short name to call the AirPort Express

Password......Type in the password of your router's WiFi network

Verify.....Type in the same password again to confirm

Click Next and the setup utility will configure the Express

I understand it will not be possible to use the Express with third party routers.

Your understanding is partially correct.

The AirPort Express cannot "extend" the wireless network produced by a third party network......but......it can "join" virtually any network provided by a third party router for use with AirPlay.

Reset the AirPort Express back to factory default settings and then set it up again to "join" the third party WiFi network and things will be just fine.

Nice work. Glad that you got the Express up and running.