Troubleshoot thermostat "Failed to connect"

Here are some steps you can take if your Google Nest thermostat is having trouble connecting to a Wi-Fi network for the first time, or after you've made some changes to the network.

There might be a "Failed to connect" message, or a g.co/nest/M21, M22 or other help code when you:

  • Install your Nest thermostat and try to connect it to Wi-Fi for the first time.
  • Reconnect your thermostat to a network whose name or other information has changed.
  • Select a different network to connect your thermostat to.
 failed to connect thermostat image

Note: If your thermostat waspreviously connected to Wi-Fi and you didn't change anything about your network, or if you're trying to troubleshoot a different Nest product, visit our article about troubleshooting Wi-Fi and connection issues.

1. Restart your thermostat

First, restart your thermostat  by following the instructions in the article below:

How to restart your thermostat

After your thermostat has finished restarting, try to connect it to Wi-Fi.

2. Restart and check your home's internet connection

Here are some general instructions for resetting your home's internet connection.

Tip: Keep in mind, your equipment may be different from what's described below. When in doubt, check the user guide for your specific router, modem, and other internet devices to learn how to restart them.

  1. Unplug your modem and router power cords.
    • You may have a combination modem/router, or they may be separate devices. All the lights on your modem and router should be off.
  2. Wait for 30 seconds, then plug your modem and router back in.
  3. Your modem and router will restart. Wait a couple of minutes or until there's steady power and connection lights. There may also be a quickly flashing data light.
  4. If you have any Wi-Fi range extenders or repeaters, restart them as well.
  5. Once you've reset your internet connection, test the connection:
    • Use another device like a phone or laptop to go online and visit a website.
      • Note: If you're using a phone to check your connection, don't use cellular data. Instead, switch your phone to Airplane Mode, then turn on Wi-Fi only.
    • You can also check whether any of the other Wi-Fi products in your home are able to connect. For example, if you have a smart speaker like Google Home, a connected TV, or a connected lighting system, check whether it's able to connect.
    • If nothing works, contact your internet service provider for further troubleshooting.

Once you're able to confirm that Wi-Fi is working, try to connect your thermostat.

Tip: You can try to temporarily connect your thermostat to another available network. This can help you diagnose possible issues. If an open Wi-Fi network isn't available, you can create a Wi-Fi hotspot with your phone. For instructions on how to do this, refer to your phone's manual.

3. Reset your thermostat's network settings

Your thermostat might have some incorrect network settings that prevent it from connecting to Wi-Fi. Try to clear these settings.

Nest Thermostat

Important: You'll need access to your Nest Thermostat to update the network and password. You can't update Wi-Fi information with the app.

Nest Thermostat E and Nest Learning Thermostat

 After you reset your thermostat, try again to connect your thermostat to Wi-Fi.

4. Check the settings on your Wi-Fi router or access point

Incompatible settings on your home's router or access point can cause your thermostat to be unable to connect to Wi-Fi.

For example, high firewall security or parental controls can block your thermostat from connecting to Wi-Fi. Refer to your Wi-Fi router or access point's documentation to learn how you can exempt your Nest thermostat from these restrictions.

If you still can't connect your thermostat after you've checked your parental controls or lowered your firewall, make sure you're using settings that allow your thermostat to connect to your home Wi-Fi. Check the article below for detailed router setting recommendations.

Recommended Wi-Fi settings

If you changed any settings, try again to connect your thermostat.

5. Check for interference

Turn off any devices that operate on a 2.4 GHz frequency, then try to connect your thermostat again. Here are some devices that might cause problems:

  • Cordless phones
  • Baby monitors
  • Microwaves
  • Bluetooth devices
  • Wireless video equipment

For more information and steps to take to troubleshoot wireless interference, refer to the article below.

Learn about wireless interference and how to troubleshoot it

After turning off any sources of interference, try to connect your thermostat to Wi-Fi.

6. Replace the thermostat battery (Nest Thermostat only)

If you have a Nest Thermostat, your thermostat might turn off the Wi-Fi connections to save power if its batteries are low. Go to the Change Nest Thermostat batteries article to learn how.

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