Advanced settings for Airport Express?

Have there been any changes in the Airport Express configuration due to firmware upgrades?

No

How can I determine the router configuration? Channels used? Carrier frequency? These do not appear in the AirPort Utility

Sounds like you are looking for more options.

Open AirPort Utility on your Mac

Hold down the option key on your Mac while you double-click on the picture of the AirPort Express

A window will open with a good deal of information.....model number....serial number.....firmware version.....MAC Addresses for Ethernet, 2.4 GHz and 5 GHz......Channels in use.....and a list of devices that are currently connected to the network.

Click on the small arrow next to each device to see more information about the connection

A few questions for you, please......

Is the AirPort Express configured to provide a wireless network for both the 2.4 GHz and 5 GHz bands using the same wireless network name?

or

Is the AirPort Express configured to use a different wireless network name for the 2.4 GHz and 5 GHz bands?

Is the name of your wireless network........

Short?......no more than 12-16 characters.......less is better

Simple?......no special characters in the name.....like an apostrophe, asterisk, etc

Compact?.....no blank spaces in the name

We ask these questions because some devices have trouble connecting reliably to a network that uses the same name for both the 2.4 GHz and 5 GHz bands.

And, some devices have trouble connecting reliably to a network that uses a long name, special characters, and blank spaces in the name of the network.

In addition to Bob's comments, and for troubleshooting purposes, try temporarily disabling wireless security on your home WLAN. See if the Internet radio device stays connected. If so, then go ahead and re-enable wireless security, but I suggest that you start with the following to see if the connection can remain stable: 0123456789abcdef0123456789

If it does, then create a wireless security password of your choosing.

The manufacturer of the internet radio told me that it wants to run on 2.4GHz.

Which likely means that the device cannot connect at faster 5 GHz levels.

So I changed the configuration to 802.11n (2.4GHz only)

This means that older 802.11"b" and 802.11"g" devices will not be able to connect to the network at all. That might be OK if you don't have older WiFi devices.

I suppose it is possible that the Grace radio was confused by the default 802.11b/g/n combo signal that the Express produces by default, and it is happier with only one choice, rather than having to choose between "b", "g", or "n".

But I have not yet determined whether this change negatively impacts other devices (e.g., AppleTV, Amazon Firestick).

These are all modern devices that will connect to an "n" wireless signal, so they should have no trouble with the current connection. They were almost certainly connecting at "n" levels previously anyway.

If so I guess I will have to create another LAN with automatic frequency choice.

Should be no need for that, since all of your devices should connect to the 802.11n signal.

I would have assumed that a device wanting to connect to an existing network would send out a query using the frequency it wants to use, and the AirPort Express would respond using that carrier frequency. If that is the case, why does the AirPort Express change frequencies at a later time?

It doesn't. If you have the Express set for 802.11"b/g/n" it provides a "b/g/n" signal at all times......older "b only" devices will connect at "b" levels, since they cannot connect at "g" or "n" levels. An older "g only" device will connect at "g" levels....since it cannot connect at "n" levels. "N" devices will connect at "n" levels. All of this happens automatically.

As I mentioned before, it is possible that the Grace device does not effectively analyze and select the right "n" signal from a composite "b/g/n" signal source.

So I don't know why the Grace radio is behaving differently from the previous one which died a few months ago. I never had this trouble with the previous Grace hardware...

I don't have an answer for you on that one. If it is the exact same model number that you had before, then it should behave the same.....assuming it is not defective.

But.....it is not all that unusual for manufacturers to change the WiFi chip inside a device to another version based on availability and shortages.....and not change the model number. So, while two devices might appear to be the same.....they are not really not.

WiFi as a general category has always been a mix of about half science and half voodoo anyway, so most of us run into situations that don't seem to make sense sooner or later.

You have not mentioned 5 GHz at all. The AppleTV and Amazon Firestick are capable of connecting at 5 GHz "n", or even "ac" levels. 5 GHz is capable of much faster speeds with less interference than 2.4 GHz signals, so you would want your 5 GHz capable devices to connect at 5 GHz levels.

The AirPort Express cannot produce an 802.11"ac" signal, so the Apple TV and Firestick would be connecting at 5 GHz "n" levels.

Here I am assuming that the you have the most recent version of the AirPort Express that is capable of producing 2.4 GHz and 5 GHz signals simultaneously.

So I changed the configuration to 802.11n (2.4GHz only). Now the internet radio runs fine.

The airport express is an old device.. even if you bought it brand new the origins go back to 2012 (even design wise it might really be 2010) for the current one.

I am not sure what setting you changed.. can you give us a screenshot.

I can only see N for 2.4ghz available in Automatic.

Anyhow whatever you did seemed to fix it so I would not be over concerned..

What I would say is that Express is not particularly good as your main wireless router.. even an older Extreme would work better.. it might really just be time to update.

Also the latest firmware 7.6.9 was not a success for a lot of people.. causing issues for some devices.. due to the KRACK firmware problems with WPA2 wireless. For some people going back to earlier firmware is well worthwhile as KRACK is mainly a client issue not router.

What version of AirPort Extreme do you have?

Is this the most recent "tall" or "tower" shaped version?.....or.....do you have an older "flat" or "square" version (that looks like a small white pizza box?

If you have an older flat or square version, look on the bottom of the device for the model number. It starts with an "A" followed by 4 numbers. Post back with that info, please.

I don't have a Sonos product here to test, but if everything else is connecting to the network except the Sonos, then the first thing that I would do is reset the Sonos back to it's factory default settings and then set it up again, so that it can pick up the changes that you have made to the AirPort Extreme network.

If your AirPort Extreme is capable of supporting separate names for the 2.4 GHz and 5 GHz networks, we'll tell you how to name them separately. Caution......even if this is possible, there are no guarantees that this will help.

Although the A1143....which Apple calls a 2nd Generation AirPort Extreme.....might be called a dual-band AirPort router, that is possibly misleading and confusing for some users.

The AirPort can provide a 2.4 GHz network.....or.....a 5 GHz network. But, it cannot provide both a 2.4 GHz and 5 GHz network simultaneously.

The 3rd Generation AirPort Extreme was introduced as the first AirPort router to offer simultaneous dual-band operation, so that model....and all subsequent AirPort versions.....were capable of providing both 2.4 GHz and 5 GHz signals at the same time.

Not sure if you were aware that the A1143 was discontinued in March 2009, so it is at least 9+ years old and as much as 10+ depending on when the AirPort was placed into service.

The average useful life of a router designed for home use is about 5 years, so you have had remarkably good luck with the AirPort Extreme. No harm in continuing to use the product as long as it continues to perform well for you, but it probably will not go much longer.

Apple officially discontinued the AirPorts in April, and they have not indicated that they have any plans for future AirPort products, so it is unlikely that Apple will continue in the WiFi router category.

However, Apple continues to sell the latest version AirPort Extreme on their online store....as long as supplies last......so if you want to stay with Apple, a new AirPort Extreme should be be good for another 5+ years. Sales appear to be brisk......since Apple continues to sell the AirPort Extreme at full price.

AirPort Extreme - Apple

I'm still using Apple routers, and haven't thought much yet about replacements at this time, so I don't have any specific recommendations for you.

If you anticipate needing increased WiFi range in the future, you might want to begin your research looking at some of the newer "mesh" systems that are appearing from a number of manufacturers.

The Best Wi-Fi Mesh Network Systems of 2018 - Lab Tested by PCMag.com