AirPort Express - Can not connect to "extended" AirPort Express

Question

Two trips to the Genius Bar tell me that I should be able to Extend my network from a new AirPort Express (n/g/b) to an older AirPort Express (b/g) using the "extend network feature". The two devices are communicating (both lights are green and the wireless channel will change on the remote device if I change it at the base station), but my MBP Core Duo 15" seems to only be connecting to the AirPort Express Base Station (n/g/b) and not to the Remote "extended" AirPort Express (b/g).
This forum seems to indicate that you can only use WDS between the newer AEX (n) and the older AEX (b/g) but the folks at the Apple Store have told me twice now not to use WDS. They said that as long as the two devices have green lights that it is working, but when I click on the Airport Symbol up in the menu bar w/the Option key it tells me the MAC address of the base station only - and when I get very far from the base station, the signal drops out even though the remote AEX is near by.
I did try setting it up using WDS and that works fine, just very slow.
Anyone know if there's a way to be sure that my MBP connects to the remote (extended) AirPort Express?

Answer 1

This forum seems to indicate that you can only use WDS between the newer AEX (n) and the older AEX (b/g)
This is correct....since the older b/g Express does not even have a setting to "extend a wireless network".
If you require confirmation, open AirPort Utility, select the b/g Express, click Manual Setup
Click the Wireless tab below the row of icons
Now look at the available settings for Wireless Mode.
"Extend a wireless network" is not there.
but the folks at the Apple Store have told me twice now not to use WDS.
They are likely telling you not to use it because the performance on your network will drop dramatically if you do use WDS. Or, they mean well, but they are just wrong on this subject. Here's why:
The only way that you can use an older "g" and newer "n" device together to provide more wireless coverage is to configure both devices for WDS. It's a Catch 22.
WDS operates only at "g" wireless levels. So when you configure the newer "n" Express to operate as part of the WDS (which you must), it becomes a "g" wireless device. You lose any "n" capability on the network
Worse still, every "remote" or "relay" in a WDS setup cuts the bandwidth of the entire network in half...50%. That's huge. In effect, with WDS, you may have a bit more wireless coverage, but you will have a "g" wireless network that operates at half speed.
but when I click on the Airport Symbol w/the Option key it tells me the MAC address of the base station only - and when I get very far from the base station, the signal drops out even though the remote AEX is near by.
The remote AX is not providing any additional wireless coverage.
They said that as long as the two devices have green lights that it is working
Nope, as you can tell by the fact that your "remote" is not providing any additonal wireless coverage.
Anyone know if there's a way to be sure that my MBP connects to the remote (extended) AirPort Express?
Your only option, (unless you add more hardware):
Configure both AX devices to "Participate in a WDS network" setting one up as a "main" and the other a "remote" . The big downside, as mentioned previously,  is that you will have a "g" wireless network running at half speed.