@RandySea2 It's not true, Deco is really a mesh.

My slave spots connect in any other spot based on best signal.

Look my home with 5 spots.

Remember to place yours slaves units with high possible SNR. Above 24db is a minimum to avoid troubles. 

check all spots and locations before place your slave spot, sometimes change 2/3mts location change your network performace.

How do you get the network map and the signal strenght display? I have no screens like that.

I have an Internet icon on the Deco app. If I click on it, I get a list of my Decos. Clicking on any one of them gives me various info on that unit. It also says where it is getting its signal from. That's how I saw that each slave was connecting to the main unit for its signal, not to the closer slave.

Also, my ISP says that  when you use a repeater, you lose half your capacity.  This would seem to apply at least to Custom_2 in your system. But maybe it applies to any device connected to a Deco other than the main Deco.

By the way, I am really hoping that I am wrong. It would be good news if there was a way to get my Deco working as I orignally thought it was supposed to.

@RandySea2 

Thank you, leogz. An hour and a half on Chat with two different TP-Link tech support people, trying to diagnose speed and connection problems, and no mention of any web interface.  It is very helpful to know about it.

I should also update on how the Deco connections changed last night. I was running some tests with my ISP that required me to swap out my Deco for my older TP-Link modem. I probably rebooted the main Deco a half dozen times, and unplugged it a couple of times. I also remotely (via the app) rebooted slave 2 once.

At some point (according to the app this morning, not the web interface), slave 2 started getting its signal from slave 1, which is closer than Main. The good news is that it now seems my Deco system is more like a mesh should be. The bad news is that for weeks it did not find the closer slave automatically. That required multiple reboots. Again, neither person in the Chat mentioned that I needed to try unplugging Decos in any particular order to get them functioning correctly.

@leogz 

leogz wrote

Network map via web ui in deco. Just http://[main_deco_ip] And for signal meter i use Wifi Explorer for Mac. If you use Windows can download Netspotapp

I wonder if you have an answer to the point my isp raised which I mentioned earlier:

Also, my ISP says that  when you use a repeater, you lose half your capacity.  This would seem to apply at least to Custom_2 in your system, since it is repeating from Custom_3. But maybe it applies to any device connected to a Deco other than the main Deco.

leogz wrote

Just turn off wifi of your provider and use wifi from deco. Just this. Also behind router use in deco in router mode. I use in this way. No worries about double NAT. i Get fully 400/200mpbs in my deco. i have 400mbps fiber link.

@leogz 

400 Mbps would be an impossible dream in the rural area where I live.

Basic service is 5 Mbps. I have 12 Mbps, the maximum.