My planned setup with either the M5 or M9 systems:

                                                                   |-------------> DECO M5 (UNIT 3)
                                                                   |

WWW ---> MODEM/ROUTER ---> SWITCH -------> DECO M5 (UNIT 1) (MAIN DECO)

                                                                   |

                                                                   |------------> DECO M5 (UNIT 2)

As I understand as per the forum: https://community.tp-link.com/en/home/forum/topic/150757?page=1 I will be able to setup an ethernet backhaul in this system using the AP mode. 

My question is if the extra ethernet point on the Deco units will still work whilst in AP mode?

For example - I want to have my PS4 plugged into DECO M5 (UNIT 1) whilst still working in AP Mode with it's ethernet backhaul and also have another device plugged in via ethernet into DECO M5 (UNIT 2) which is also using the ethernet backhaul.

Will all this be possible? Thank you!