@WifiRoland 

In AP mode, you can connect Decos to your home network any way you want. 

@Alexandre. 

Thank you for your reply.

The strange thing is that i found a manual from TP-Link when using a specific Dutch provider (Ziggo), see: https://www.tp-link.com/nl/support/faq/2879/. 

They advise the following:

Step 10 - Enable fast roaming (which i can understand)

Step 11 - Enable AP mode

Step 13 - When using more DECO's and ethernet, use daisy chain or star topology to connect the 2nd and 3th.

And this i cannot understand and make me doubt the product and technology. In fact, the modem from the provider is just acting as a switch. So in my opinion it should not matter how to connect the DECO's to the LAN netwerk when using AP mode. There is even a small switch that connects to the modem and in my opinion the DECO's can be mixed connected to the modem or switch.

I can understand that in router mode the 1st DECO has a WAN port and a LAN port, and all other DECO's should connect to the LAN port when using the ethernet backhaull.

But this shouldn't be the case with AP Mode.

Is this just an error in the manual/article? Or is there some technical requirement in place?

I do experience some issue with the DECO M4, connection seems to be slow at some places even when using a cabled ethernet connection to the DECO, so i want the exclude all potential issues first. 

@WifiRoland 

Check this FAQ article: General questions about Ethernet Backhaul feature on your Deco. Ignore first section and Picture, because they only apply to Deco running in default Router mode. Even if it is not specifically said there.

Scroll down to Q1: Can I connect all the Deco units directly to my home modem/router?

Here is my home network configuration:

Hitron CODA-4582 Modem Router (you can google its specs)

It has four Gigabit ports:

Port 1 - Main Deco M9 (actually, long Ethernet cable from that port to switch1, then cable from switch1 to switch2, then another long cable from switch2 to Main Deco)

Port 2 - Satellite Deco M5, directly connected with short Ethernet cable

Port 3 - Networking printer

Port 4 - File server

I also have another Satellite Deco M9 connected by WiFi backhaul to Main Deco M9.

That works for me. My ISP download speed is 300Mbps, I am getting that much with speedtest on smartphone when connected to Main Deco and when connected to Satellite Decos. I enabled only 5GHz band in Deco for Main network, disabled 2.4GHz, because I have good coverage and don't want devices to switch to slower 2.4GHz on their own.

@Alexandre. 
 

thank you for your clear answer, very helpfull!

So it is clear that the Ethernet backhaul is not an issue for me, thanks.

I think that because the area where there is a problem has more wall's I need to add an Deco. However, the m4 doesn't has a dedicated wireless backhaul (e.g. the M9 has, not sure about the M5) so this influence max speed, when the m4 is connected through a wireless backhaul, connection is not above 60-70 Mbps. So probably need to add 2x M9. First a wired backhaul to 1xM9 and then wireless to a second M9. 
 

The other M4 are in open areas and have no issue. And, the M4 that had the issue was only able to be place low to the ground which doesn't help for performance because there is no clear line of sight.

Thanks again!