Ideally, you would want to create a roaming network for all three levels. However, this would require that all of the base stations be connected by Ethernet. If this is possible, I would strongly recommend this method.
If running Ethernet is not possible, you may want to consider using Powerline adapters to create an Ethernet network using your electrical circuit.
If Powerline is not the way to go, then your next option, which would allow only wireless connections between base stations, is to configure them for an extended network. However, for this option to be successful, the main base station would need to be located on the 2nd floor with a remote base station on each of the 1st & 3rd floors as this type of network does not allow for a relay station like the older WDS configuration.
For the last 2 years I've running a WDS network in a 3 storey building quite successfully*. Time Capsule in basement (connected to internet), Airport Express on ground floor. Reception in basement and ground floor is
great, 1st floor is OK - I can stream video to it but signal strength isn't amazing.
When I set this up originally the "wizard" made setting up the WDS network really easy. I recently had to reset everything and it wasn't as easy as I remember!
From what I've read WDS can be a bit of a pain and it doesn't utilise all the bandwidth. If all the devices in your are wireless-N devices there is an option to use the "Extend Network" option which apprently is much easier to setup and has better data-transfer rates.
* As a side note I updated the firmware to 7.6.1 yesterday and it broke the WDS setup.
This is easy to set up and you have the correct idea of how to do it. Don't worry about WDS (Wireless Distribution System). That was the old way of accomplishing this type of set up that is handled automatically with the new routers since they now have multiple antennas that support MIMO (multiple-in/multiple-out). There is also no need for running etherent cables, this is all handled wirelessly.
Start with the main router that is connected to your ISP's modem. Set it up as you normally would making sure you following the instructions below for the settings under the 'Wireless' tab.
Set the 'Wireless Mode' to 'Create a wireless network.' Give the wireless network a name and check the box next to 'Allow this network to be extended. (See screenshot below.)
Note: 'Radio Mode' and 'Radio Channel Selection' are up to you. Set as is appropriate for your environment.
Now let's set up the adjacent routers.
Set the 'Wireless Mode' to 'Extend a wireless network.' Type in the name or use the drop-down menu to select the name of the wireless network that you've already created. Check the box 'Allow wireless clients.' Use the same passord that you used for the main router. (See screenshot below.)
You're done. You should now be able to move around to all three floors of your building and your wireless devices will connect to the closest router with the strongest signal using the same password throughout.
If you find areas of the building where the signal is spotty you can fill them in with less expensive AirPort Express routers. The settings are pretty much the same.
It should but it will depend on the settings for 'Radio Mode.' Try it on 'Automatic' first (as shown in the first screenshot). It is suppose to allow connections from all 802.11a/b/g/n devices. If you run into problems with certain devices not connecting try one of the other settings. You only have to set this on the main router. The other routers will self-configure based on the main router's settings when they connect to extend the network.
I am in about pretty much the same situation with a building of 3 floors and the following limitations:
- I access the Internet on the top floor (4G router Broadband, signal strenght issue elsewhere)
- Airport Extreme 5th gen next to the modem, also covering top flor with Wifi
- Airport Express 2nd gen on mid floor, extending network wirelessly
- Too much loss of WiFi signal between top and bottom floor
- No ethernet network
- Powerline to sensitive for interferrence, some power plugs don't even connect
Ideally I would like to extend on bottom floor with another Airport Express, but as I understand from Apple Support and from Tesserax above, this is not possible. All extending devices must apparently be directly connected to the primary device. I could use an Express in client mode, but I also need WiFi coverage so this is not an option.
Can any of you confirm if this is really the case and if there is a workaraound?
If your response is to my post above, those screen shots are from v5.6.x of the AirPort Utility. The newer v6.2 is a little different, as you can see from your own screen shot, but functionally the same. Some options from the old utlity have been moved and can be revealed when you click on the ‘Wireless Options…’ button. The checkbox for ‘Allow this network to be extended’ is no longer required. A network can be extended using any other AirPort router as long as you know the wireless network name and password you want to extend.
Here is a screenshot of the current v6.2 AirPort Utility showing the settings of a configured wireless network using a Time Capsule.
Here is a screenshot of the current v6.2 AirPort Utility showing the settings of an Airport Express configured to extend the wireless network created by the Time Capsule.