I Have 6 BE65 units. The main one is wired to the internet in my garden room, then connected via CAT6 to another unit in the house, which then hard wire connects to a further unit. These work fine as long as they're hard wired. However, no matter what I do, all units working wirelessly want to connect to the main unit only, they completely ignore the units much closer to them that have Ethernet backhaul. So if I add one that connects to the main unit (with a VERY weak signal), all other wireless decos want to connect to that unit, resulting in them disconnecting randomly and giving terrible speeds.
I've gone as far as resetting the whole system, adding them one by one then when it gets to the 4th unit which needs to connect via wireless, I wrap the main unit up the garden in foil so it can't 'see it' and lock on to that unit. This results in the app refusing to add the new deco. It will find it eventually but refuses to synchronise settings. 
I thought there would be some intelligence in this system to join a node with the strongest signal, but they just won't do it. I've tried swapping units to no effect. Setting the 'connection preference' from auto to a specific node has absolutely no effect either, they just ignore that and carry on trying to connect to the main unit.

what's going on here? I bought 6 of these to cover my needs and looks like I'll have to return them all