For three years, my Honeywell (Resideo) WiFi thermostat worked great, then suddenly would not communicate to the WiFi App and reported a WiFi Radio Error. After two weeks of troubleshooting and always blaming the thermostat, we realized that the problem may be the 2600 Routers USB 3.0 interferance with 2.5 GHz WiFi the Thermostat uses.
The Thermostat would work from the app for a few minutes, then report WiFi Radio Error and not respond to the Resideo App, but the wall-mounted unit would still operate normally, It just could no longer be controlled by the app over WiFi.
After spending two weeks troubleshooting, working with Resideo Support (who were very helpful), and even replacing the thermostat with a new unit, the problem still occurred. We eventually realized it had to be the documented issue where USB 3.0 causes interference with 2.5 GHz WiFi. As the WiFi router (Synology 2600) uses a USB 3.0 port with a thumb drive to store security data, the router USB port, being so close to the WiFi antennas, was the interference source and caused the Honeywell thermostat WiFi to go offline (see picture). Due to this known issue, the router can be configured to downgrade the USB port to 2.0, eliminating the WiFi interference issue and after that, the Thermostat worked fine. I realized at this point that I had configured the router for USB 3.0 around the time the problems started to improve the write time to the USB drive.
I guess this is why the routers come with USB 3.0 disabled as the default.
The Thermostat would work from the app for a few minutes, then report WiFi Radio Error and not respond to the Resideo App, but the wall-mounted unit would still operate normally, It just could no longer be controlled by the app over WiFi.
After spending two weeks troubleshooting, working with Resideo Support (who were very helpful), and even replacing the thermostat with a new unit, the problem still occurred. We eventually realized it had to be the documented issue where USB 3.0 causes interference with 2.5 GHz WiFi. As the WiFi router (Synology 2600) uses a USB 3.0 port with a thumb drive to store security data, the router USB port, being so close to the WiFi antennas, was the interference source and caused the Honeywell thermostat WiFi to go offline (see picture). Due to this known issue, the router can be configured to downgrade the USB port to 2.0, eliminating the WiFi interference issue and after that, the Thermostat worked fine. I realized at this point that I had configured the router for USB 3.0 around the time the problems started to improve the write time to the USB drive.
I guess this is why the routers come with USB 3.0 disabled as the default.