Airport Express A1392 failing to connect to wifi

OK, let's see if the AirPort Express will work using an Ethernet cable.....not WiFi to connect to your main router.

Perform another Factory Default Reset or a Hard Reset on the AirPort Express again. The Hard Reset is easier for most users, and it accomplishes the same thing. To try the Hard Reset, power up the AirPort Express and let it run for a minute. Then, hold in the reset button for 7-8 seconds and release. Allow another minute for the AirPort Express to restart again.

Connect an Ethernet cable from one of the LAN <--> Ethernet ports on your main router to the "O" Ethernet port on the AirPort Express. There are usually four Ethernet ports on most routers, so you can use any of these ports.

Open up AirPort Utility again and click on the Other WiFi Devices button

Click direct on AirPort Express xxxxxx

AirPort Utility will take a few seconds to analyze the network settings and then suggest the correct setup for the AirPort Express. The window will look similar to the example that you see below.

Network Name......Type in the same name as your current WiFi network

Base Station Name.....Type in a device name........AirPort Express......for example

Password......Type in the password for the WiFi network

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

Click Next, and AirPort Utility will try to set up the AirPort Express

If you see a message of Setup Complete, click Done. There should be a green light on the AirPort Express at this time.

In this type of setup, you must leave the Ethernet connection from the router to the AirPort Express in place at all times. In other words, you cannot disconnect the Ethernet cable because the AirPort Express has been set up to use an Ethernet connection.

You mentioned that the AirPort Express had stopped working a few years ago, so if that is the case, it unlikely that it will start to work correctly again.

If you have performed a Factory Default Reset a few times, are selecting the right Wi-Fi network, and entering the password for the network correctly and the Express continues to experience errors, there is not really anything else that you can do at this point.The Express is likely defective, at least for the purpose that you are trying to achieve.

It is possible that the Express might work correctly though, if it is configured to connect to your Wi-Fi router using a permanent wired Ethernet cable connection rather than a Wi-Fi connection.

Post back if you want to try that type of setup and are not sure of the details.