For thermostat wifi, Google has separate articles: one for the thermostat during setup, one for the offline state and a general Wi-Fi and connection guide for Nest products. Bring the thermostat and router close for setup, confirm the network name and password, and use a supported band. If the thermostat cannot find your network, restart the router and modem, check the router is broadcasting and not hiding the name, and check whether it is on 2.4 GHz or 5 GHz.
The checks in more detail
If you changed router or password, Google's new wifi guide explains how to connect the device to the new network in the Google Home app, which may include forgetting the network first. A thermostat that keeps dropping may have a power problem, since Google notes it disconnects from wifi when it lacks system power, so read the No power steps. Signal problems come from distance and materials, so move the router or add a mesh node near the thermostat's wall. Turn off VPNs on the phone used for setup. Restart the thermostat from Settings, Restart, which keeps settings.
If it still cannot join, a factory reset may be needed, and you should write down your wiring and settings first. Check that the router's DHCP is on and no filter blocks it. Test signal at the thermostat's wall with a phone, since the thermostat sits in a hall and the router may be far away through several walls. Keep the thermostat away from metal boxes and thick ducts, since they block radio signals in a way a router cannot fix. After a router change reconnect the thermostat the same day.
When you change your wifi name or password, connect the thermostat the same evening while you remember the change, because a thermostat that stays on the old network for weeks is easy to overlook until the app says offline. Google lists network extenders among the things that can confuse a Nest device, so if your home uses an extender, test the thermostat with the extender switched off or on a separate network name before concluding the thermostat itself has a wifi fault.
Differential
Likely causes of “Nest thermostats will not stay connected to Wi-Fi”, and how to tell them apart
- 1
A changed router or password
What separates it The thermostat cannot join the network because the router or the password has changed
How to confirm Reconnect it through the app or the thermostat's menu, entering the new network details
- 2
A weak signal
What separates it The wifi drops because the signal at the thermostat is weak
How to confirm Move the router closer, or add a mesh node near the thermostat, to strengthen the signal
- 3
A power problem
What separates it The wifi drops even with a good battery because the heating system gives the thermostat too little power
How to confirm Fix the power from the system, by checking the C wire or fitting a Power Connector
- 4
Router filtering
What separates it The router rejects the thermostat because its filters or DHCP settings block it
How to confirm Check the DHCP and the filters on the router, and allow the thermostat to join
- 5
A hidden network
What separates it The thermostat cannot find the network because the router hides its name
How to confirm Make the router broadcast the name of the network, at least while you set the thermostat up
Before you touch a setting
Record this first — changing settings destroys the evidence
- Whether the wifi password has been changed recently
- The signal strength shown on the thermostat
- Any power alerts that the thermostat shows
Try in this order
0 of 7 completedConfirm the network works
ReversibleConfirm the network works for other devices, since if none work, the fault is with the router.
Check name and password
ReversibleCheck the name and the password, remembering that the password is case sensitive when you retype it.
Restart router and modem
ReversibleRestart the router and the modem, and wait for all of their lights to settle again.
Restart the thermostat
ReversibleRestart the thermostat, which keeps all of your settings and often clears a stuck connection.
Reconnect in the app
ReversibleReconnect the thermostat in the app or on its menu, choosing the network that you use now.
Check power alerts
ReversibleCheck the power alerts if it keeps dropping, since weak power can make the wifi disconnect.
Reset last
ReversibleReset the thermostat last, and note the wiring first, so that you can rebuild your setup.
Model-specific
What is true of this model and not of its siblings
- Learning Thermostat 4th gen
- Has its own setup steps.
- Older models
- Some older models use a different reset menu.
Stop boundary
When this stops being a self-service repair
- !If it cannot join after a restart, contact Google Nest support
- !If power alerts appear, follow the No power steps
- !If the router blocks it, check the router
Evidence ledger
Sources behind this answer
Wifi and connection.
Changing wifi.
Offline steps by model.
Restart versus reset.
The company and its products.
Exact questions
Common questions
Why won't it join wifi?+
The usual reasons are a weak signal, a wrong password, or a power problem.
Can power cause wifi drops?+
Yes, power can cause wifi drops, since a thermostat with too little power cannot hold a connection.
Should I note wiring before a reset?+
Yes, note the wiring before a reset, so you can put everything back correctly.
Can DHCP matter?+
Yes, DHCP can matter, since the router must hand the thermostat an address.
Who can share access to the thermostat?+
A home Admin can invite Members and other Admins, and each person then uses their own Google account.
How do I contact Google Nest support?+
Use the Google Home and Nest Help site, and have your model and the exact message ready when you contact them.
Can I remove the thermostat from my account?+
Yes, remove it in the Google Home app before you sell it or give it away, so that the new owner can set it up.
How long after a power cut does it reconnect?+
It usually takes a few minutes to restart and reconnect, so wait before you judge the thermostat to be faulty.