Yes, it works. I have 5 Decos, X60 and M5 working in AP Mode behind a pfSense Firewall.

@knorde On The main router DHCP server (pfSense) I've set fixed IP leases for each Deco MAC Address. Works perfectly, each Deco with an IP Easy to remember. Best Regards.

@Momcho, they are right. Our fault was to choose the wrong product or vendor. I Will remember that answer next time I choose another networking product.

@Alex. At firmware 1.5.5, Deco M9plus has a "Smart" DHCP which sometimes messes my network even in AP mode. In my case, I have Deco M5, firmware 1.6.0 which allow to disable this feature,so I've...

@mrlee2 In my installation, Deco source selection does not apply If ethernet is used as backhaul, only to wifi connected Decos.

@TP-Link Overall I am very satisfied with version 1.6.0. I was having trouble to put Decos to use ethernet infrastructure, but as soon as the New version was installed all Decos connected to the main...