I've just had ethernet cables installed around my house which has resulted in a change in my Deco unit set up. Previously I had the main unit connected to my router via ethernet,  the first satellite connected to that main unit wirelessly, and the second satellite connected to the first satellite wirelessly. The network operated as I expected it to. The network was set as Access Point mode for the decos. The wifi from my router is disabled. 

Now though, as I've had ethernet cable installed to rooms on the far side of the house from the router, I now have:

Main deco unit in same room as router connected directly to the router via ethernet exactly as before.

First satellite connected to main deco unit via wireless. 

Second satellite on opposite side of house connected directly to the router via ethernet.

There are no switches between the wired deco units and the router.  

I was expecting the second satellite to now utilise ethernet backhaul, however, it still says on the app that it is connected to the first satellite deco via wireless.

However, to make matters stranger, when I do an download speedtest next to the second satellite, I get pretty much my full expected download speed (500Mbps), which it would NOT get if it was actually connecting via wireless to the first satellite. 

And if I do a speedtest next to the main deco unit, which in my previous setup would have got me full download speed, I'm now only getting about 50Mbps, even when stood right next to the main deco unit. It is like the main deco unit is now going through the second satellite via the first one. 

I was expecting that by connecting the second satellite with an ethernet cable directly to the router that would improve the overall wireless signal in the house, as that room was pretty poor signal due to brick walls, however, while technically that room's wireless has got better, the speeds elsewhere have dropped off. 

What am I missing and/or doing wrong?