Just had my thermostat go off line and not comeback even after a factory reset. The phone would control it right in front of the thermostat ,but not in the other rooms. Had the same IP and looked like it should work. Went to my router cleared the DHCP settings for all devices, and immediately the thermostat came back with a new IP and instantly connected. Interestingly enough, I had a similar issue with the previous Honeywell wifi thermostat 6 months ago. Thought I would give it a try. It might be my router and DHCP settings since I let all devices reserve their addresses.