I just installed brand new a 3-node Deco M9 Plus (US) system and updated to latest firmware. It is working great with all of my devices, except my two Honeywell T9 smart thermostats. The thermostats are in good working order and have no problems connecting to my old Asus or Linksys routers, but no luck with the Deco.

I have already tried many of the suggestions found elsewhere in the forum: Mesh OFF, Fast Roaming OFF, dedicated guest network on single band, rebooting, factory reset and reconfigure everything, etc. I need a real solution, not just guesses, to this issue. Has anyone here on the forum experienced this issue and gotten resolution? 

TP-LINK SUPPORT -- Please help