Airport network extension issues

I have extended my main Airport Extreme with 3 Airport Expresses (2 directly, and one of the expresses extends one of the two that are directly connected) throught the house. Now I am having issues with some of the things that are connected to the wifi. For example, on my Xbox and Apple TV, whilst watching Netflix on the extended network, it will randomly disconnect. I dont know if this is because it is switching between routers or if that doesnt matter at all since it is all the same connection. I don't know if this also happens on my other wireless clients, but it is more noticible on the Apple TV and Xbox, since I usually am streaming Netflix and it will just disconnect. Also, on my Xbox, the extended network doesn't even show up. I'm frustrated do not know what to do. This is what the setup currently looks like

Try the Wireless diagnostics on your Mac.
This will give you an idea of the signal quality you are getting in various areas in your home.
Hold down option and click on the wifi icon in the menu bar, then select open wireless diagnostics.
Enter your password then select the Window menu and then Utilities.
Select the performance tab to get a real time signal reading. You are looking for a sustained SNR reading of 20 or higher. Even if you have full bars you may not have a great signal quality.

It's also possible that you have greater than 10 devices on your network as that is the limitation of the older AE WAPs.