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

Solving Honeywell WiFi Thermostat Connection Problems

Explores solving Honeywell WiFi thermostat connection problems.  We find all of these on our Honeywell RTH9580WF thermostat. But this info applies about as well to Honeywell’s other WiFi thermostats. These include 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 WiFi thermostat does not see your network during setup.

Solution

Make sure you power up your router. Also check that your WiFi SSID is visible.  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 credentials manually.

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 a Honeywell RTH9580WF thermostat. Displaying the -Select WiFi Network- screen. Showing the Other... option.
Honeywell RTH9580WF thermostat. Displaying the -Select WiFi Network- screen. Showing the Other… option.

1.2 Wi-Fi Network Parameters have Changed

Problem

That is, the access point password, network name, or network security settings may be different now. This often happens when you install a new router.  So to avoid this problem, program the same network data into the new router that they old one had.





Solution

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

Some thermostats need a hard reset to change the network to which they connect.  But others, such as the RTH9580WF, let you change the network settings without resetting.

Picture of the -Menu- screen. Showing the WiFi setup option.
The -Menu- screen. Showing the WiFi setup option.

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 WiFi thermostats talk to the network using the 802.11g WiFi standard.  Transmissions like this occur in the 2.4 Ghz. band.  Now 2.4 Ghz. is also a popular band for many devices.  These include other WiFi networks and non WiFi devices. These include cordless phones, microwave ovens, baby monitors, Bluetooth speakers, and remote controls.  Indeed there’s a lot of traffic in that band thus.  That’s especially so in crowded apartment buildings or closely spaced housing.  So now and then, your Honeywell thermostat may not connect 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.  Now the thermostat connection may go bonkers after you power up a certain device.  If so, then that’s likely the device interfering.  So try moving this appliance further away from the thermostat and router.

Reposition your router closer to the thermostat.

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

Picture of calibrating a Honeywell WiFi thermostat temperature. Using a fridge freezer thermometer for this.
Calibrating a Honeywell WiFi thermostat temperature. Using a fridge freezer thermometer for this.

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 a Honeywell WiFi Thermostat, mounted but powered down.
A Honeywell WiFi Thermostat, mounted but powered down.

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. Then they fail to perform as well as they did when new.  The transmission power of the thermostat may fall very low.  So low that its signal can no longer reach the router.  WiFi thermostat parts are particularly subject to this sort of wear dur to their always-on duty.

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, then replace it to head off any future 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: Keeps Losing Connection

Consider the following possible causes and fixes if your thermostat frequently loses that connection.

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. Then 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 router is not getting 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 up and running for your thermostat to connect with the Honeywell 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 login page.
The Honeywell Total Connect Comfort web site login page.

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 defective wires, outside equipment failures, and so on.  Now your thermostat may indeed connect to your WiFi access point  Yet it still may show an error message.

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

 Solution

Wait a few hours for the Honeywell servers to come 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. This might show which channels have the least traffic.

Other Posts About the Honeywell WiFi Thermostat

    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

References for Solving Honeywell WiFi Thermostat Connection Problems

    1. Honeywell WiFi Thermostat Official Product Page