I have my 3 Deco's setup in AP mode. The main Decon goes into Untangle which is my firewall / router amongst other things too. When in access point mode it would appear that Deco QOS is not available...

I have the Deco M5 3 pack running well in AP mode with a Gig switch. Latest firmware. What I have found is that the main unit must be the first one turned on after upgrading and switching to AP mode...