Orbi and Lennox iComfort thermostat

I too have had a connectivity problem as described.  My thermostat was working fine and installed on 5/16 until late summer of 2018.  In June of 2018 I installed my Orbi system without a problem, including my thermostat and all other wifi devices.  In September, my Orbi connection to my Lennox icomfort thermostat became intermittent and then virtually noexistant.  I disconnected Orbi and reconnected to my former router and the thermostat connects to the wifi as it should.  I have many deadspots in my home that Orbi corrected, but the thermostat connection is unacceptable.  Help!