Speed drops on adding third extender

[ErikM]

I have been using the BT Flex Extender 1000 for a couple of years now with no problems.
I've recently had the need to add another room to the network, so bought another pair.
Following the instructions for adding a third unit worked fine. The original unit gets speeds of 80+ mbps, the new unit was averaging between 40 and 50. (figures using google's internet speed test)

But the next morning, the download speed to the computer plugged in to the new unit dropped below 1 or 2mbps and upload was 0.
I've since tried it in different sockets in various rooms connected to different computers/laptops (including the socket in the room where I've been using the original extender, with the original computer), and switching between the two new units in the box.
Same thing is happening each time; decent connection to start with, dropping to nothing after a period of inactivity.

Are they misadvertised as being able to join an existing network, are these units defective, or is there something else I need to do which isn't in the (very light) manual to stop the connection idling away to nothing?

[Les-Gibson]

You can expand an existing network buy adding a new one to it as long as they're all on the same ring main and plugged directly into the wall socket, don't plug them into extension leads.

You should only have one extender connected to your hub.

Make sure you have disabled Smart Setup. What is Smart Setup on the BT Hub? How can I turn it on and off? | BT Help

[gg30340]

Try contacting the technical help line  08081006116 option 1 to see if they can help. 

[ErikM]

@Les-Gibson 
I'm not sure if you read my post, or just skimmed it, but literally nothing here was helpful. Just comes across as an attempt to farm ratings.
I only have one extender connected to the hub; the same one that's been there without problem for 2 years.
I have added a third extender to the network. Even plugged into the same double socket that I've been using the original extender in for 2 years with no problems, the connection drops out. It makes the initial connection just fine, it then drops down to nothing after being left idle.

[ErikM]

@gg30340 
This was helpful, cheers. Will give that number a try in the morning.

[Les-Gibson]

@ErikM 

perhaps you can point me to the bit tat I missed because I still can't see anywhere in your original post where you have clearly answered any of the questions I asked. Maybe I need some new batteries for my crystal ball