@David-TP Yes David, the Asus router used to be put where the T3-Deco is, and that router using the LAN port just fine. But I want to get mesh network and using 1 wifi name so I replace 3 routers to 3 X60 though. 

Is there anything would you recommend to get the ethernet backhaul working? Should I try to install one more tp-link switch before connect the LAN port to T3-Deco? 

Many thanks.

  @David-TP 

thank you for your reply. 
 

My setup is:

modem --> sf1005d (about few cm) --> main deco at 1st floor (about few meter); sf1005d --> T2-deco is on 2nd floor (I dont know exactly how long is the cable but i guess it maybe 5 meters); sf1005d --> T3-deco is on 3rd floor (i dont know exact how long is the cable, my guess is not over 10 meters), from wall sockets on 3rd floor to deco is few cm away though. 
 

because all the wires are inside the wall, it is impossible to run cable from 2nd to 3rd floor though. 
 

is it better if i setup other way like 

modem --> deco main --> switch ---> satelite on 2nd and 3rd floor and set deco as router. Would that make any different?
 

any other suggestions?

  @David-TP 

Hi David, it has been a busy week for me. But today I got time to try out your recommendations though. Also, I bought new tp-link switch ls1008g (giga switch). The story are:

1. Tried to change deco T2 to T3: it still not works. 
2. Tried to setup router->deco main-> switch->deco satellite and set as router: T3 still not connect through Ethernet backhaul. 
3. But there is 1 little interesting thing though, after change to the new switch, if I plugged Ethernet cable to T3 continuously then T3 showing not connected though. When I unplugged, T3 connect to T2 wirelessly like before. 
 

Is there any other suggestions that you would recommend?

thank you. 

  @TP-Link 

I am looking to add a mesh system to my house to replace my existing wireless. I was looking at the X60 and using 3 of them since I have an extremely long ranch house. I had the whole house wired with Cat 6a cable 4 years ago (plain Cat 6 to the cameras). My wired network is a bit complex/complicated and I want to make sure I will not have a ethernet backhaul problem with the configuration. I plan on putting all three X60's in AP mode and continue to let my modem/router handle it's duty. Logically I believe this should work, wondering if there will be any practical problems. I am attaching a picture of my proposed setup.

Having similar issue. The "Kitchen" node is connecting by WiFi, backhaul not working. 

I have an unmanaged switch connected to the Main Deco, and then all nodes connect to the switch. 

Two work perfectly (Attic and Bedroom); they connect by backhaul and no issues. 

I speed tested the ethernet cable supplying the "Kitchen" node and it's giving me full speeds as per my ISP, similar to other cables. 

  @David-TP 

I’m having a similar issue. In my network topology, I have a Deco XE75 as main unit and 3 other units (2 XE75 and another PX50) connected to the main unit through a tp-link ls1008g switch.

Only one of the XE75 units is not recognizing the Ethernet backhaul, as images bellow. I tested the network cable, as well as changed the switch port without success.

  @fhreis 

What will happen if you power off Satellite Deco which does not recognize Ethernet backhaul: will another Satellite switch to WiFi backhaul or not?