Airport extreme/express network setup

Question

i'm sure this has been covered in general but lan equipment and requirements vary widely (plus most of my wireless experience is w/non-apple routers), so here goes. i have the following hardware
airport extreme (802.11n) running 7.5.2 (might downgrade to 7.4.x based on comments in this forum) connected to cable modem
2 airport express (v6.3) connected wirelessly to ap extreme
1 airport express (v6.3) connected via ethernet (wd powerline) to ap extreme
what i'd like:
ap extreme base to be the only SSID & DHCP server on the network.
the 2 wireless expresses to provide wider coverage in the main house.
the express connected via ethernet to provide wireless signal/access in the detached guest house (trying to run it wirelessly does not get a strong enough signal, hence the powerline ethernet), but only as an extension to the extreme base.
when a device (laptop, phone, etc.) connects, it should use the closest / strongest wireless signal, but always think there is only 1 network/connection config. and, when one moves between house and guest house, connected device will auto 'roam'.
whoever set this up, set the extreme to be running in WDS mode (WDS main). however, it complains that it is the only WDS device on the network (see next ???).
the 2 wireless expresses are set to 'Participate in WDS' (WDS remote)
in order to get the ethernet-connected express to work, i had to give it its own SSID and set it to 'Create wireless network'.
it does work, but there are 2 networks, no roaming, and error message on ap extreme base re:WDS config.
questions:
1) what mode should the extreme base use ('Create wireless network' or 'Participate in WDS network')?
2) what settings (WDS or wireless) for the wireless expresses?
3) what mode should the ethernet-connected express use ('Create wireless network', 'Participate in WDS network' or 'Join wireless network')?
4) anything special i need to know to get the roaming to work reliably?
5) any suggestion (due to missing questions :-)?
tx for any info. i could try all the permutations & combinations of config (actually, i've already tried a number of them , but tired of running up/downstairs and to/fro resetting devices, so i thought i would ask for help from people with more experience background.
mack

Answer 1

Hi, mackiemesser. Welcome to the forums!
So if I understand correctly, your setup looks like this:
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• Express #1, Express #2, and the Extreme should be set to "Participate in a WDS."
• The Extreme needs to be told that Expresses #1 and #2 will be WDS Remotes. (You'll have to enter their MAC addresses.)
• Expresses #1 and #2 need to be told that the Extreme will be their WDS Main. (You'll have to enter its MAC address.)
• Express #3 should indeed be set to "Create a wireless network" but should use the same SSID and password that your other wireless network uses.
• All Expresses should be configured to operate in Bridge Mode. In Manual Setup, click "Internet" in the toolbar and choose "Off (Bridge Mode)" from the "Connection Sharing" popup menu.
• The Extreme should not be in Bridge Mode. It should instead "Share a public IP."
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A few suggestions:
• Write down the MAC addresses of all your Extremes. This saves a lot of time when you're setting up the WDS.
• Sometimes after you change the WDS settings for one AirPort on the network, it confuses the other AirPorts in the WDS, and you get network problems until all of the AirPorts agree on WDS information. In this case, if you can't see an AirPort in AirPort Utility, connect that AirPort to the computer via Ethernet. In fact, it might save time to gather all your AirPorts and plug them in next to your computer for the WDS setup process so that you can easily connect via Ethernet if necessary.
• Using a WDS dramatically decreases your network performance. Every time you add a WDS Remote, you decrease your maximum network speed by 50%. Newer AirPorts support 802.11n and have a feature that allows you to extend your wireless network without as much overhead as a WDS, but all AirPorts in the wireless network that's extended must support 802.11n.