Optimal set up for Apple Extreme wired Wi-Fi network

I presume the BT router is distributing IP addresses to my network?

That is correct.

if I give the Airport's static address in their configuration, do I need to restart my entire network so there aren't conflicts, etc ?

That would be a good idea. It may not be absolutely necessary, but I would do this if possible.

Or do I just set them up as static with the ones the currently have (so clearly not used) and good to go?

This all depends on whether you want to set up "Static" on the AirPorts using AirPort Utility, in which case, the "Static" IP address will be the same IP address that is currently assigned to the AirPort.......or.......whether you want to set up dedicated Static IP addresses on your BT router, assuming it has that capability, which it should. These settings might be under an Advanced Option or something like that on the BT Router, so you'll need to be able to get into the settings on the BT router to make changes. BT Support may or may not be willing to help you with this.

the router will know not to assign these to anything new in the future and to the extent devices join / restart they will not use something already using a static address?

That is correct. If you decide assign Static IP addresses from the BT router, it would also be a good idea to assign a Static IP address to your printer. That way, it will always get the same IP address.

Or do I need to reserve these somewhere in the BT router so that the IP addresses are not used by another device?

That is an option if you want to assign specific IP addresses to the AirPorts......like the example that I gave above where the AirPorts get 192.168.1.100, 192.168.1.101 and 192.168.1.102 addresses or similar. The advantage would be that it will be very easy to identify any of the AirPorts since they have easily recognized IP addresses.

That being said, it is not a strict requirement to use Static IP addresses at all, but it is a good idea to do so.

You both mentioned the network in "Off (Bridge mode)" - but what about the Wi-Fi network ? (which is in "Create a wireless network") Is that the correct settings for all 3, and should I always have channel settings as automatic/

Here is an important tip for you. If any AirPort connects to the network using an Ethernet connection, then the correct Wireless setting will always be "Create a wireless network". Golden Rule.

You would want to use the Automatic setting for Channel selection to allow each AirPort to scan among other WiFi networks in your area and then select the best channels available for each AirPort automatically.

I suppose that you could guess at trying to set a channel manually, but which channel to choose? Even if you guess well at a good channel to use, other WiFi routers in your area are automatically changing their channels to look for the best setting, so the "right" channel now may not be the best setting in a few hours.

You may find that the AirPorts are using different channels when you check or they might be using the same channels. I pay no attention to this at all.

6 I have all three set up as "Create a wireless network" in wireless mode with ethernet cables plugged into the bottom port labelled with for each device

That is fine assuming the Airports are configured in bridge mode.. i.e... under Network tab you have selected.. Off (bridge mode)

7 I have ticked the "5Ghz network name" for each but then entered the same name as the existing SSID (not sure if this is advised or I don't need to do this.

There is no problem doing this but it is unnecessary.. Airport by default use the same name for both bands.

Any advice on the primary set up or whether one should b designated primary (even if not directly plugged into the router)?

This is trial and error..

If everything works fine and you don't have any Airport disappear from network and all of them provide the wireless service you want.. don't worry.. be happy!!

On the other hand you might find the Airports don't behave so well.. post back because there may be improvements that can be made.

The key one I would do anyway is use Static IP on the Internet tab.. and set IPv6 to link local only.

Post back if you need the details.

One of the problems with a "roaming" network.......the type of extended network that you have where the wireless access points all create a wireless network using the same wireless network name, security and password........is that some devices will switch access points to pick up the best signal as they move about the house and some devices will not.

Unfortunately, Apple provides no settings to automatically adjust or improve things. In general, Mac laptops will usually do a nice job of automatically switching from one access point to another as the device moves from a location near one access point to another location near another different access point.

But, iPhones and iPads and other portable devices in general will not do this very well, if they do it at all. For example, if my iPhone is connected to my office AirPort Extreme and I walk the iPhone to the den where another AirPort Extreme is located, the iPhone will not switch to pick up the stronger signal from the den AirPort.

Sometimes......the iPhone might switch over after a few minutes......and sometimes it won't. The only way that I can make sure that the iPhone connects to the den AirPort when it moves to that location is to temporary turn off the WiFi on the iPhone, wait a few seconds, then turn the WiFi back on. Then.....the iPhone will usually pick up the stronger signal from the closer AirPort. Switching Airplane Mode on and then off again will do the same thing as turning the WiFi off and back on.

You will have to experiment to find out what works best for you on your network.

As far as setting up a Static IP Address for each AirPort, the simplest way to do this would be to switch things over on the Connect Using setting in AirPort Utility from "DHCP" to "Static".

If your "main" router......which is the BT router......provides settings to assign a Fixed or Static IP Address to a connected device on the network, you could set things up that way as well. You may need the MAC Address or Ethernet ID for the AirPort in this type of setting. You can see that by opening AirPort Utility, and clicking on an AirPort. In the smaller window that appears, hover your mouse over the name of the AirPort and look for the Ethernet ID.

Give the Airports an easily identifiable IP address......maybe something like 192.168.1.100, .101 and .102 or 192.168.1.150, .151 and .152, etc.

LaPastenague's recommendation to use the Link Local Setting for IPv6 on each AirPort is a good one.

You won't be able to configure any of the AirPorts as a "primary" router, they are all equal in Bridge Mode, which is the correct setting for each AirPort that connects to the BT router.

Just fill it in yourself.. it is one of those stupid things.. by default it is 192.168.1.254 which you can use or use public IP like 8.8.8.8 or fill in both spaces.

It performs no functions in the network.. so the error makes no difference.. so filling it in is just to keep everything happy. The Airports are being used as dumb Access Points.. and all routing / DHCP serving is handled by the router.

Bob suggested using a strict set of IP addresses just to make things easy.. And I 100% agree.. so you can change the IP to say

192.168.1.200

192.168.1.201

192.168.1.202

You can then exclude a range of addresses in DHCP of the BT modem router.. just set it to 199 as top address say.

Here is my version of the same thing..