@TP-Link 

Hi,

1. The satellite unit will flash red once it loses connection. 

2. Connection doesn't restore unless I remove the satellite or reset it, but then it loses connection if the system is in router mode.

3. The main units always worked. It's only the satellite dropping connection. It happens within 10 minutes of establish connection every time.

4. Both the main and satellite work with wired back haul in access point mode or with the satellite in wireless mess. The connection drops from the satellite only in router mode.

5. The topology goes like this:

Arris modem -> <cable> Main AX5700

                     -> <cable> Satellite AX5700

My whole house is hardwired. The Arris sits in the garage where all the Ethernet cables all goes to. Both AX5700 units are connected to the Arris modem directly. 

@gordec 

See this: General questions about Ethernet Backhaul feature on your Deco

From that document:

In Router mode: Only the main Deco could be connected to your home modem/router. Other satellite Deco units should be connected behind the main one, just as the “Star Network” shows. If not, they may be in a network loop and cause unexpected dropout issues.

@Alexandre. 

Thanks that makes sense. I think I can make it work that way. I just need to put the main unit in the garage near the Arris modem. Right now access point mode works fine. I'm not using all the router mode features, so it's ok like that.