I have had a Deco E4R 3 Pack for a couple of years now. When using the Deco, I have always turned off the WiFi in the router to reduce the non-mesh signals in the flat.

Yesterday my old copper landline was upgraded to FTTP Full Fibre. This meant that instead of coming into my flat from a 1st floor window in a back bedroom like the old copper line, the the new fibre comes in from the front, in the kitchen, so I have had to reverse the order of my Deco units and move one

The ONT, router and VOIP are working properly but the Deco units are struggling. My flat was built 1950 with internal brick walls up to 300mm thick.
I was able before, to link the main Deco via Ethernet cable to the Deco in the lounge which was line of site to the Deco in the hall. I had an Ikea Hub, a Hive Hub and a Zigbee Hub wired into the Hall Deco through an Ethernet splitter box.
ie Router>Main Deco Bedroom > wired> Lounge Deco > WiFi > Hall Deco> Ethernet splitter and 3 Hubs
In all there were 13 devices connected. 9 by WiFi and 4 Wired

Now I have ONT>Router>Main Deco Kitchen> WiFi > Lounge Deco 
                                                                                   > WiFi > Bedroom Deco
The Ikea Hub, Hive Hub and Zigbee Hub are wired into the Main Deco through an Ethernet splitter box.

With the new arrangement, Deco automatically set up in Router mode.
The Lounge Deco has a Medium WiFi signal but the Bedroom Deco has a Fair WiFi signal that occasionally drops out,  
Because the Bedroom Deco signal drops out occasionally, I tried setting up the Deco mesh in Access Point mode.
All the WiFi devices connect but the Wired connections no longer show in the Deco App. I can see the lights flasshing correctly on the Ethernet splitter but none of the devices conncted to the Hubs respond.

What am I doing wrong?