@Tony ok so that is exactly what I'm doing I pulled up the first google result for changing DNS on Deco (https://www.tp-link.com/us/support/faq/1600/) and just went down that road so my DHCP server...

Is Pi-Hole supported w/ Tp-Link? I have setup my 3 stations successfully. When then going into settings and setting the primary and secondary DNS to my pi-hole(s) it's working fine. I see requests...

@ggilman any update on this? I have the exact same issue - setup pi - set it as only dns server for deco - works great - try and reboot deco - deco is dead have to hard reset all 3 and setup entire...