@hornetster 

In Access Point mode, Deco provides WiFi coverage, while network is still managed by your router. If all you need is better WiFi coverage for your place, running Deco mesh in AP mode is the right solution.

Because in AP mode all content filtering and bandwidth throttling features of Deco are turned off, you will be getting maximum WiFi performance Deco can deliver.

If you plan to wire some of Deco nodes with Ethernet, you will have complete flexibility how you want to do it.

All wired and wireless devices on your network, including those wired directly to the router, will be on the same router subnet and can communicate with each other.

You will not need to wire Main Deco directly to the router, could be to the switch. Also, you will not need to pass all network traffic through the Main Deco. If you have network switch, you can just connect Main Deco to one of its ports. In case you have heavy wired network traffic over gigabit Internet link, that would be preferred setup. Less stress on Main Deco CPU if it only serves wireless devices.

See What’s the difference between Access Point mode and Router mode on the Deco?