Hi,

My issue is as follows,

I have 3 x Deco X60 and 2 x Deco M4.

My provider is Virgin and I have 1gb internet.

The hub 5 is set to modem mode and connects directly to the main X60, the X60 connects to a TP link 8 port gigabit switch which then feeds a second X60 upstairs via wired backhaul which works perfectly achieving download speeds of around 900mb however when I try to connect the other X60 or one of the M4's in my lounge via ethernet cable either directly to the main deco or to the switch it knocks out the entire mesh system taking them all offline. I currently have to position the third X60 in the kitchen wirelessly connect this to the main deco and then wirelessly connect a M4 in my lounge to the kitchen X60 to provide internet coverage in the lounge. This in itself would not be a problem except certain devices will not run from the lounge deco when plugged into the switch connected to the lounge deco, currently the virgin 360 box, phillips hue hub and nvidia shield will not detect an  ethernet connection from the switch connected to the lounge deco and will only pick up an ethernet connection if I connect them to the switch connected directly to the main deco. I already have two ethernet cables directly from the switch connected to the main deco running the virgin tv box and the phillips hue hub and don't want to have to run a third for the nvidia shield. A lot of rambling I know but I'm struggling to describe the issue but it appears I cannot connect either the X60 or the M4 in the lounge directly to either the port on the main deco or the switch connected directly to the main deco without it taking the whole system offline with no internet connection.

I was trying to achieve ... modem to main deco, main deco to ethernet switch, ethernet switch to upstairs deco creating wired backhaul (this works perfectly), ethernet switch to lounge deco creating wired backhaul (this when plugged in takes all deco's offline).

Not sure if this will make sense to anyone but any help would be appreciated. 

Point of note of the ethernet cables run to the lounge one is exactly the same as the one that connects the upstairs deco without an issue and the other is a brand new cat 6.