I've picked up an S4 three pack.

I have the same issue. I have one unit at the back of the house as the main deco into the internet. Hallway deco is at front of the house and the two show a solid full link between them.

Directly above the Hallway Deco is my front bedroom where my Office deco lives. This unit is connecting all the way to the back of the house and the throughput speeds reflect it.

I get 240Mbps on the main deco (internet is 250Mbps), i get 190ish on the hallway and then 10 on the office,

The office one has my network switch connected to it with my wired devices. Typically would be this link that's running the slowest.

There is NO way the signal from the backroom is stronger than the one from directly below.

Is this a true mesh?

I'm about to open a support ticket.

I have this same issue.  One side of the house has the Internet connection with main deco, 2nd deco in the middle of the house, and 3rd deco is in the garage on other far side of the house.  Garage always wants to connect to the far away main deco and skip the 2nd middle one.  Its so frustrating. Please let us select the path!

I have found that the connections can vary from day to day. When restarting after one of our relatively frequent power outages, all the remotes always start out connecting to the main Deco. In a day or so, connections readjust to more of a appropriate mesh.

                      Main

                    /            \

Dining Room                 Upstairs

           |                                  |

Cabin Living room         Cabin bedroom

Several days later, I may see a new set of connections, also an appropriate mesh for my home/cabin, though slightly different.

                         Main

                      /             \

Dining Room                Upstairs

                                             |

                                     Cabin bedroom

                                             |

                                     Cabin Living room

It may not make any difference for anyone else, but I suggest checking your connections again after a day or two. You might also try defragging your hard drive.

Oops, defragging was the Customer Support universal solution of a different era. I meant, reboot all your Decos, starting with the main one and continuing in order of closeness.

@RandySea2 it makes sense that connections change. Especially with higher frequency ranges like 5ghz the connection strength is more sensitive to things like air humidity. So when for whatever reason the deco unit restarts or disconnects it might or might not find the power threshold to the main deco good enough to connect with. 
 

the main problem though is that there seems to be a strong preference for each deco to connect to the main deco instead to its closest neighbor. So in essence, deco acts as a star/hub&spoke design, not as a mesh. 

@Olafmol 

I agree that there is a real problem that TP-Link has ignored despite more than a year of reports.

If I had known this before I bought the Decos, I would definitely have bought something else. But since it seems to be working adequately, if unpredictably, for me, I'm pretty much stuck.

I certainly would not recommend the Deco to anyone else.

@MackPhoenix62 this is ridiculous, really! Same problem here...

This is not the cheapest mesh solution out there, TPLink is not supposed to be a Chinese knock off company also, thought we've been more than one year waiting on a solution for this.

Disgraceful!

@TP-Link_Deco . It is must to have a selectable . All these suggestions are just patch work which does not work . I bought 2 more devices without realising it has this problem and now returning both of them.

@TP-Link_Deco . It is must to have a selectable . All these suggestions are just patch work which does not work . I bought 2 more devices without realising it has this problem and now returning both of them.