What is the correct configuration for WDS between T/C and AIrport Express?

Yep, you're correct Bob. It was up and working for maybe a minute or two, then it was back to Expresses popping on and off the list in Airport Utility.

I've just tried to get things back to WDS, but the neither Express is visible now. I could see them both after doing the factory reset, but as soon as I configure them to be part of the WDS, they drop off.

I've seen in other discussion threads that it's a good idea to clear out all keychain items related to the Airport network as well as clearing out all memorized networks. I guess I'll try that in the morning and see where it takes me.

Honestly, 2 years of running a WDS network, and it all goes blooey with one upgrade and a thoughtless Okay. I wonder if Apple doesn't do this on purpose to sell new hardware.

but as soon as I configure them to be part of the WDS, they drop off.

Drop off of what? Do you mean that they "disappear" from AirPort Utility? If yes, of course they "drop off" because they have left the temporary connection that was established to configure the Express and they have now joined your "main" network.

As soon as you click Update at the conclusion of the configuration steps.....and you see a message that the settings have been storred.......close AirPort Utility immediately.....and wait 40-45 seconds for the Express to restart to a green light.

Now, you must log on to your normal wireless network again by clicking the AirPort icon and selecting the name of the network that you want to join. If your settings are correct, all devices that have been configured will be on the same network. If you now open AirPort Utility, you will "see" all of your devices on the network.

If you do not get a green light 40-45 seconds after you click Update, then one or more of your configuration settings are not correct.

Yes, the two Expresses disappear from the Airport Utility device list, which isn't what I expected given my previous WDS configuration.

Reading your message Bob, it appears that the Expresses should drop off the Utility device list, and reappear once Airport Utility is restarted.

I have reset the Expresses to Factory, which results in the Time Capsule being green-light happy, but both Expresses have amber lights, solid amber in Airport Utility, and flashing amber on their LEDs.

I am now trying the use the auto config to extend the range of the main (TC base station) wireless network.

I've give the AEs the same password as the TC, and chosen the network created with the TC. I then hit Update, and close Airport Utility and wait a minute.

Physically checking the AEs, I see amber flashing on both, but on re-opening Airport Utility, everything has green lights.

Now, maybe it's because the two AEs are 802.11g devices, so the WDS needs to be in place. Having green lights on Airport Utility and amber flashing on the devices isn't a good sign.

When I do get this figured out, I'll write up a definitive set of instructions.

it appears that the Expresses should drop off the Utility device list, and reappear once Airport Utility is restarted

This is true as long as you have logged on to your "normal" wireless network first. Remember, AirPort Utility is using a temporary network with a name like Apple Network xxxxxx during the configuration steps. When you click Update, the Express switches from the Apple Network xxxxxx network to another network that you have named under the Wireless Network Name during setup.

So, you must log on to the network that you have told the Express to join.

I'm not sure why this concept seems to be so difficult for so many users to understand.

You configure the Expess on one network (Apple Network xxxxxx)....but, tell it to join another network when you click Update.....so you have to log on to the network that you told it to join in order to "see" the AirPort Express.

Make sense?

I've managed to rebuild everything, but the key for my situation was to bring all the devices into the same room, removing any issue of wireless network interference. With all three devices reset, here's what I saw in my Airport Network Chooser on the Menu bar:

But you don't need to change networks here to configure the devices, as Airport Utility does it for you when you change the Airport device:

As soon as you hit Manual Setup, if you aren't using the network generated by the selected Airport device, Airport Utility asks you if you want to change networks. So far so good.

First, I configured the Time Capsule, using Manual Setup, as this is the only way to configure the WDS network (Thanks Bob for the reminder on that!):

Note the "Allow this network to be extended checkbox below the Network Name. This must be checked for the WDS network to allow the remote stations to be added.

Configuration for the WDS Base Stations looks like this:

For each Remote Base Station, you need to set the Wireless tab fields exactly the same as the Main Base Station, or your network will have problems. Also, note that in the Wireless Network Options, it's probably a good idea to check the Network Robustness option, especially if you've got cordless phones in your house.

On the WDS tab, the images below show the entries for one of the Airport Expresses I've added to my WDS network as Remote Stations.

Here's the Wireless settings for one of the Remote Base Stations, below. Note that it's identical to the Main Base station settings, except for the Radio Mode name, as my AEs are only 802.11g devices.

Apple Discussions won't let this post get any bigger, but there are a couple of other screen grabs, but AFAIC, the key to this is bringing all the Airport devices into the same room. That way you can see what's happening, and you'll know there is little chance of radio interference. Everything is now back up and running, better than before, and the new version of Airport Utility prompts you to save a profile, and you can have multiple profiles for your setup, so rebuilding a network is as simple as selecting the last known good Configuration Profile from the pop-up list. I'll add the screen grabs to another post.

Here are the remaining screen grabs from my Airport Utility configuration. I hope this helps others solve their WDS issues quickly.

The image below shows the settings for one of the WDS remotes. Note the Allow wireless clients checkbox. This is the part that extends the same network.

And, below is a screen grab showing the new Configuration Profiles selector. This is going to save some time if I ever need to rebuild again, or extend the network further. Of course, if I suddenly get really flush and could afford to redo the hardware to all 802.11n devices, WDS is no longer necessary. Still, it's better to have the tools and struggle to use them well, than to wish for the tools that don't exist.

But you don't need to change networks here to configure the devices, as Airport Utility does it for you when you change the Airport device:

If only it worked this way for all users all the time. There are thousands of posts from users who report that AirPort Utility cannot "see" their device, or nothing turns up when AirPort Utility scans for devices.

As soon as you hit Manual Setup, if you aren't using the network generated by the selected Airport device, Airport Utility asks you if you want to change networks.

This also confuses many users as well, who instinctively choose "no" when asked if they want to change networks, (they don't understand that they "do" need to change networks) so they click "no" and then can't find the device that they need to configure.

That is why I advise users to look for the Apple Network xxxxxx first and log on to that network. Then, you don't have to "switch" networks. You are already on the correct network to "see" the device that you want to configure.

I have detailed these thoughts to Apple Support several times, requesting that they add more explanation about this to the bare bones setup manual. So far, no luck.

Thanks for your very detailed response. Glad that you got things going!