@woodrjh 

 

OK so I finally figured out what happened...

 

I have a three Deco X20 set up, all have backhaul ethernet LAN connections.

 

I moved my main deco to a new location, but didn't notice that it's wired connection was not working.

 

It was then power cycled, and after a while, the whole network was "disconnected" from the Internet.

 

The Main Deco was then connected back to the LAN and reset, as it wasn't working and had the "red" LED showing.

 

At this point, the APP was unable to "see" the network as the Main Deco was unreachable and no longer available.

 

I deleted the network from the APP, and then attempted to recreate the network.

 

This was not possible, as the reset Main Deco wired connection was still able to "see" the remaining two Decos on the LAN and refused to configure my new "Main" device. Just kept on saying that the Ethernet connection was not available. Not a helpful error message really, when what is meant was that other Decos were on my network talking to it.

 

The only way to recover this was to use the reset button on all three Decos, with them disconnected from the Ethernet LAN.

 

Each device was then effectively new out of the box.

 

The main Deco was reconfigured as per the installation instructions. This was a little difficult, as it was not possible to configure the device directly into AP mode. The work around for this was to configure it with a static IP on my existing network (I don't use the Deco as a router, only in AP mode) and then switch it into AP mode once it was configured.

 

This finally gave me a Main Deco with the correct SSID operating in AP mode.

 

To connect the other two simply required them to be connected into the Ethernet LAN and powered on. After a while, they are "discovered" by the Main Deco and can be configured.

 

This is not at all an obvious to diagnose issue, and the error message from the APP is utterly misleading and prevented my from being able to figure out what was happening.

 

The only way that I got a clue as to what was happening was to use wireshark packet capture on my network switch (which has port mirroring) and look at the traffic from the Main Deco when it was failing. I could see that the other remaining Decos were "talking" to it, and this was what was preventing it from being configured on the LAN.

 

Reset all fixed it.

 

You have been warned... This is not documented as an issue. Perhaps a more useful APP error message would be something like "I can see other Decos on the network, so reset them first, before trying to configure a new Main Deco" instead of "Ethernet port is not working"

 

Enjoy!