Honeywell wifi thermostat not able to connect

You mentioned that it was working before so that would mean something changed to create this problem. Since TMO has not issued a new firmware in the past couple months, that can't be the cause. The only thing that likely changed on your TMO gateway is the public IP.

I would contact Honeywell again and tell them the following:

• TMO gateway will frequently change it’s public IP just like cell phones do
• The TMO public IPs frequently show geolocations that are no where near the physical location just like cell phones. Like a couple hundred miles away. As I type this, my public IP says my location is 180 miles south of my gateway.

If either of these cause problems with Honeywell, it could explain why it no longer works since Honeywell services are expecting your thermostat to have the same IP and/or same geolocation when you initially set it up.

You could test this theory by removing your thermostat from Honeywell app and then factory reset to do setup all over again. I'm not sure what all you lose by doing that and keep in mind, all that will do is confirm this theory.

You should also know, if it turns out this is the problem, there is nothing TMO can do about it right now so you may not even have a solution unless Honeywell can make it work.