Picture of the Honeywell wireless thermostat, displaying its -Lost Wi-Fi Signal- message.

Solving Honeywell WiFi Thermostat Connection Problems

This piece explores solving Honeywell WiFi thermostat connection problems, as we find on our Honeywell RTH9580WF internet controlled thermostat, although this info applies about as well to Honeywell’s other wireless thermostats, including the RTH8580WF, VisionPRO TH8320WF, VisionPRO 8000, et al.

Solving Honeywell WiFi Thermostat Connection Problems

By this, we mean that the t-stat will not connect to your home Wi-Fi network. It may or may not have been able to connect prior. Common causes for this type of failure to connect we list next.

1.1 Wi-Fi Network Not Found in Scan

Problem

Your wireless network does not show up in the list of in-range networks that the t-stat discovers during a WiFi scan during setup.

Solution

Make sure you power up your router, and that your WiFi SSID is not hidden (being broadcast).  Most routers broadcast the network name SSID by default.  But you may have hid your SSID for more security.  If so, then your network will not appear in the in-range networks list when the t-stat scans for networks.  So you’ll have to enter your network name manually as well as the security protocols it uses (WPA, WEP, WPAT, TKP, AES, …).

For hidden WiFi networks, many Honeywell smart thermostats have an  Other  button. Use this button to cover the case where your network does not appear in the list.  When you press that, the t-stat prompts you to enter your network details as discussed.  But be careful to avoid typos though.  A wrong network name, password, authentication, or encryption protocol entered here will keep your t-stat from connecting.

Picture of the Honeywell RTH9580WF thermostat, displaying the Select WiFi Network screen, with the Other... option highlighted.
Honeywell RTH9580WF thermostat, displaying the Select WiFi Network screen, with the Other… option highlighted.

1.2 Wi-Fi Network Parameters have Changed

Problem

That is, the access point password, network name, or network security settings may have changed.  This often happens when you buy a new router.  Unless you program set it up with the same network data, a new router almost certainly will use a different SSID and password.





Solution

Gather your correct Wi-Fi network name and password.  Then set up the t-stat to connect to that wireless network.

Some t-stats need a hard reset to change the network that they try to connect to upon start up, such as the RTH8580WF does.  But others, such as the RTH9580WF pictured next, allow you to go in and change the network settings without a factory default reset.

Picture of a Honeywell Wi-Fi touchscreen thermostat, with the Wi-Fi setup option highlighted.
Honeywell Wi-Fi touchscreen thermostat, with the Wi-Fi setup option highlighted.

1.3 Router May Need a Reboot when Solving Honeywell WiFi Thermostat Connection Problems

Problem

Your router may have received an update, experienced a power surge, or caught a firmware bug.  These gotchas may corrupt the RAM in the router.  Thus, they can interfere with how it responds to connection requests from Wi-Fi based appliances, like the Honeywell wireless thermostat.

Picture of the Asus RT-AC87R Wireless Router, Front View, Installed and Operating on office desk.
Asus RT-AC87R Wifi Router, front view, installed and operating.

Solution

Restarting the router clears out working memory, and allows the router to start again from a known-clean point.  Rebooting a router / access point often restores proper router operation.

1.4 Interference Degrading the WiFi Connection

Problem

Most Honeywell wireless t-stats talk to the network using the 802.11g WiFi standard.  Transmissions like this occur in the 2.4 Ghz. frequency range.  Now 2.4 Ghz. is also a popular frequency band for many devices.  These include other Wi-Fi networks as well as non Wi-Fi devices such as cordless phones, microwave ovens, baby monitors, Bluetooth speakers, and home theater system remote controls.  There’s a lot of traffic in that band thus.  That’s quite so in crowded apartment buildings or closely spaced housing.  So now and then, your Honeywell thermostat may fail to connect or to maintain connection with your router due to this interference.

Solutions

Get rid of the source of the interference if possible. For starters, try turning off any cordless phones in your house and see if the problem goes away.  If so, replace your phones (including the base unit) with one that runs on different frequencies than 2.4 Ghz.  Many of the newer wireless phones operate in the 1.9 Ghz. band.  They design these not to interfere with WiFi.  But don’t buy one if you’re not sure what frequencies it works on.

Do likewise with other wireless devices as well.  Try turning them all off and see if the problem disappears.  Then, turn them each back on, one by one, and watch the reaction of the t-stat after each.  If the thermostat connection goes bonkers after you power up a certain device, then that’s likely the one causing the interference.  So try moving this appliance further away from the t-stat and router.

Reposition your router closer to the t-stat.

1.5 Thermostat Too Far Away from your Wireless Router when Solving Honeywell WiFi Thermostat Connection Problems

Picture of the Honeywell RTH9580WF thermostat on same wall as a typical fridge freezer thermometer, used for thermostat temperature calibration.
Calibrating Honeywell RTH9580WF thermostat temperature, using a fridge freezer thermometer, with Both on same wall.

Problem

Even though the signal strength of the Wi-Fi network might show as full strength, connection may still fail.  This is due to multi path signals between your router and t-stat and / or interference from nearby devices.

Solution

Move the router closer to the t-stat.

Or, try the answers in problem 1.4 above.

1.6 Defective or Misconfigured Router / Access Point

Problem

Check this by trying to connect to your wireless router with another WiFi device.  Try this with a tablet, mobile phone, laptop, or even a desktop computer via Wi-Fi.  Now if these clients fail to connect, but did connect before this t-stat outage occurred, then try the following.

Solutions

Try resetting your Wi-Fi enabled router to factory defaults,.  Then, when it comes back up, make the needed tweaks to it to fill your network needs.  Finally, try again to connect the thermostat.

If that measure fails, switch to a different router.  That’s not too expensive these days.  Indeed, routers like those that meet minimal speeds of Honeywell wireless thermostats, are quite cheap (under $40), and reliable.  Check around for them on eBay.  Now Honeywell wireless thermostats need little internet bandwidth. So generally they work very well with even the cheapest wireless routers.





1.7 Broken Thermostat

Picture of the Honeywell RTH9580WF Internet Thermostat, mounted but powered down, snapped onto wall plate.
Honeywell RTH9580WF Internet Thermostat, mounted but powered down, snapped onto wall plate.

Problem

If none of the above fixes solves the problem, you may have a defective thermostat.  Indeed, over time, most electronic parts like those in the Wi-Fi radio in the thermostat, weaken and fail to perform as well as they did when new.  The transmission power of the thermostat may fall to such a low value that its signal can no longer reach the router.  Wireless thermostat parts are particularly subject to this sort of wear, as the thermostat maintains constant (24 X 7) contact with the Honeywell Total Connect Comfort  servers via the internet.

Solution

Replace the thermostat.  Try a different Honeywell wireless thermostat.  Like wireless access point electronics, thermostats do age too.  If you’re thermostat is more than a few years old, it’s probably time to replace / upgrade it anyhow, especially if it’s causing issues.

1.8 You May Find a Defective Furnace when Solving Honeywell WiFi Thermostat Connection Problems

Problem

Your furnace supplies 24 volts AC to most wireless thermostats, via an internal power supply.  This energy reaches the t-stat via the connecting wiring from the furnace to thermostat.  If this AC supply becomes intermittent, noisy, drops or raises in voltage a lot, then the thermostat often fails.

Solution

Check that the AC voltage at the thermostat terminals is 24 volts AC, plus or minus ten percent. If not, call a furnace repair technician, and have her troubleshoot your furnace and repair its power circuitry.

Solving Honeywell WiFi Thermostat Connection Problems – Thermostat Keeps Losing Connection

Consider the following solutions if your Honeywell wireless thermostat is able to connect to your home Wi-Fi network, but frequently loses that connection for the various reasons discussed in this section.

Picture of the Honeywell wireless thermostat, displaying its -Lost Wi-Fi Signal- message.
Honeywell wireless thermostat, displaying its -Lost Wi-Fi Signal- message.

2.1 Internet service Temporarily Unavailable

Solution

Try accessing the internet through another device on the same Wi-Fi network as your thermostat.  If they do not work either, then notify your internet service provider about the problem, and wait for service to return.

2.2 E02 and E43 Error Messages 

Some Honeywell thermostats display these errors when the Wi-Fi connection has been lost or cannot be initiated due to the reasons discussed above. 

Solution

Execute items in the first major section above to troubleshoot this problem.

2.3 Router Lost Power

Perhaps your wireless router has been disconnected from mains power.

Solution

Verify that the router has power and is up and running, by executing items 1. above.





2.4 Modem Lost Power

Problem

In some installations, the cable / DSL modem and router access point are not in the same box.  Yet all of these components must be powered up and functioning properly in order for your thermostat to establish a successful internet connection with the Honeywell infrastructure servers.

Solutions

Check the status lamps on the modem, router, and wireless access point to verify correct modem function.  Any red or blinking lights could indicate a problem.

Check that you can connect to your network with other wireless devices, as described in items 2.1 above.

2.5 Honeywell Total Connect Comfort Servers may be Offline

Picture of the Honeywell Total Connect Comfort web site, displaying its login page, with active account info filled in.
Honeywell Total Connect Comfort web site, displaying its login page, with active account info filled in.

Problem

Sometimes, they take down Honeywell Total Connect Comfort servers to apply upgrades.  Or, your own internet may have gone down due to storms and power outages in your area.  There could be downed wires, outside equipment failures, and so on.  While your t-stat may indeed connect to your Wi-Fi access point, it still may show an error message like the one shown in the orange area in the next picture.

Picture of the Honeywell wireless thermostat, displaying its -Lost Wi-Fi Signal- message.
Honeywell wireless thermostat, displaying its -Lost Wi-Fi Signal- message.

 Solution

Wait a few hours for the Honeywell servers to be brought back online.

2.6 Wi-Fi Channel Too Busy

Problem

Most routers broadcast on WiFi network channels 1, 6, or 11.  It may be that the channel your network is using is very busy with neighbors’ network traffic.

Solution

Change your router’s Wi-Fi channel.  To do that, log into the router’s admin pages.  Also note that the router will likely reboot after you apply the change.  Try channels 1, 6, or 11, and see if the lost internet connection problem persists.  If you have access to an Android tablet or phone, you can try Ampd’s Wi-Fi Analyzer to see which of these channels has the least traffic.

Other Posts About Honeywell WiFi Thermostats

  1. Honeywell WiFi 9000 Color Touchscreen Thermostat Review
  2. Change WiFi Network on Honeywell Thermostat RTH9580WF
  3. Honeywell WiFi Thermostat Registration Instructions
  4. Reset Honeywell WiFi Thermostat, How To Instructions
  5. Fixing WiFi Problems on Honeywell RTH9580WF Thermostat

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References for Solving Honeywell WiFi Thermostat Connection Problems

  1. Why is my Honeywell Wi-Fi device not connecting to the Internet?  at HoneywellHome.com

Revision History

  • 2020-04-19: Added more tags.
  • 2019-06-02: Tuned the targeting for ‘Solving Honeywell WiFi Thermostat Connection Problems’, and added more links and tags.
  • 2017-01-29: Originally published.
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