Using an old Airport Express for airplay with a non-Airport router

Try a Factory Default Reset on the AirPort Express a few times.

reset airport base station

Power off and restart your main WiFi router

Restart your Mac as well

If still no luck, try an iPhone or iPad for the setup of the Express

Home Screen > Settings > WiFi > Set Up New AirPort Base Station > AirPort Express

If you continue to see the same error message, the Express is defective and will need to be replaced.

The setup utility thinks that the name of your wireless network is Shmendypete-2.4.

If that is correct, then in the box next to Base Station Name......type in a short simple device name that you want to call the AirPort Express........example......Express

In the box next to Password.......type in the WiFi password that you use to connect to the Shmendypete-2.4 wireless network.

In the box next to Verify......type in the same password again to confirm

Click Next and follow the prompts

The Base Station Name does matter. Use a short phrase......anything you want...... for the Base Station Name.....no more than 16 characters.......with no special characters like a $ (dollar sign), or a ' (apostrophe), etc and no blank spaces.

SamsExpress would be OK

Sam's Old AirPort Express would not be OK

All that you are really doing here is connecting the Express just like another new WiFi device would connect to your network. You would select the name of the WiFi network to join, and then enter the password to connect.

Not sure which "trick" did it, but glad that it worked.