Nest Thermostat won't connect to wifi

[JohnH3]

I recently disconnected our router for about 20 minutes while moving some furniture.  When I reconnected, everything in the house worked, except the Nest Thermostat.  Since then I have tried everything I could find online and have had no success.

My phone and ipad will connect to the thermostat, but the wifi connection fails every time (I have tried various things about 10 times).  I started by restarting the thermostat and then followed all of the troubleshooting, including a factory reset and disconnecting from my account.  Still nothing.

I should also mention that I am a pretty experienced at getting devices to connect.  I've found that "smart-home" devices occasionally are tricky to connect, but have always been able to get them to connect. 

The router is close to the thermostat and the iphone or ipad are close to the thermostat when I try to connect.

The power to the thermostat is fine as well.

I'm thinking the thermostat is faulty, but that really seems strange since it is only about 3 or 4 years old.

[Frustratedddd]

You say your are pretty experienced at getting devices to connect, so I expect you have tried connecting via a hotspot to your phone? Are you saying that's what you have done? Just proves the thermostat is faulty or not.

[JohnH3]

Yes.  I tried to connect to a hotspot from my phone.  No success there either, and I was standing about 3 feet from the thermostat.

[patoz80]

Same issue on my thermostad, It  is about 10 month old, it was working fine until 2weeks ago, It disconnected and never connected to wifi again.  I tried most of the troubleshoot steps.  It tries to find wifi but it can not find any wifi. 

Model : Display-3.7

Serial number: 09AG01AJ47220GRP

[Patrick_Caezza]

@patoz80 

At 3.7 volts the thermostat will shut off the Wifi to save battery.

How do you have it wired? Is there a C wire installed?

Which Nest thermostat do you have?

[patoz80]

here is the exact same issue

Re: Nest Thermostat Suddenly can't find ANY wifi n... - Page 3 - Google Nest Community

[Frustratedddd]

I expect you have tried the Hotspot as well?

This is not a new problem, wifi chips have been faulty for years, but that doesn't mean your one is!!

Probably better to start your own convesation otherwise your issue will get lost in this one.

[Patrick_Caezza]

@JohnH3 

Are you getting any type of error message?

Is your Wifi name showing up? Is any wifi name showing up?

How do you have the Nest wired? Is there a C wire installed?

[JohnH3]

Thanks @Patrick_Caezza,

I'm not sure if it is an error message, but the Google Home message that says "Couldn't connect to Wi-Fi" ends with 3.10.

The wifi name shows up, as does our "guest" wifi name (i've tried to connect to both).  My ipad and iphone both display the typical number of wifi networks (ours, neighbours, etc.)

It is a gas hot-water heating system, so there are only connections for heating and there is a C wire.  It has worked fine since it was installed late in 2020.  The thermostat will operate the system (it is working and shows the normal display but also shows that it isn't connected to wifi)

The battery shows as "good", but also shows as 2.938V with an impedance of 958 mOhm.I read in another thread that the batteries don't charge when the system is off, but I'm not sure if that applies to me.  The system is always on and the thermostat is always powered, but the heating is set to "Off" at the thermostat.  This morning, I turned it back on.

[JohnH3]

@Patrick_Caezza

Just to clarify my response above, it is now Monday morning and the heat has been on since Saturday (on but not calling for heat).

The voltage is now showing as 2.943, so not much change since Saturday.

It is hard-wired with a C.  The power connections are C-W-R

Another "power" screen shows Vin: 39.905, lin:385, PS:C-385

In response to the wifi question, the thermostat doesn't show me which networks it "sees".  I have to connect through Google Home, so it is the wifi networks that my ipad or iphone sees.

Thanks

[SoriaD_]

Hello @JohnH3 

Thanks for posting in our Nest Community about this disconnection on your Nest thermostat. I apologize for all the inconvenience. I'm here to help you with that.

I completely understand how frustrating this situation is. Let me lend you a hand to find the solution. 
Please fill out this form to forward this case to my support team. We are so happy to assist you.

Feel free to reply to this post when you complete it. We will contact you to continue searching for an answer.

Best regards,
Douglas.
 

[JohnH3]

Thanks Douglas,

I filled out the form.

JohnH3

[JohnH3]

Unfortunately, after trying all of the connection tips and working with Google Nest support, it was determined that my thermostat is defective and at 4 years old, is well past it's one year warranty.  Google does not offer any kind of discount in this circumstance.

I'm going to try one last thing: even though the unit is powered, including a "C" wire, and the batteries report as "good", I'm going to try replacing the two 1.5v AAA batteries to see if that makes any difference.

[JohnH3]

As mentioned above, I tried the last thing....

I replaced the batteries with new AAA Duracell's.  In a few minutes, the Nest Thermostat displayed a message I hadn't seen before: "Batteries Low".  Because I knew the batteries were not low, I removed them and cleaned both terminals on each side of the two battery compartments on the thermostat.  I re-inserted the batteries and didn't get the batteries low message again.

I then proceeded to try, once again, to connect to Wi-Fi using the Google Home app on my iPhone.  It quickly connected to my phone and I went through the setup steps to connect to Wi-Fi.  It connected in about 10 seconds and I am back in full operation.

I'm truly surprised that low batteries prevented a Wi-Fi connection, particularly because my thermostat is connected to power, and has a C wire (C-W-R).  Also surprising is that the thermostat reported the old batteries as "good", when obviously they weren't.  I had read other posts that said the batteries needed to be at 3.8v for wifi to work, but didn't think that applied to me because of the wired power connection.

[luciaaa]

Hi, @JohnH3,

Thank you for reaching out to the community and for your efforts to resolve the inconvenience. I'm glad to hear that your Nest thermostat has successfully connected to Wi-Fi.

Regarding your concern, even with a C wire, batteries can degrade over time. This can lead to fluctuations in voltage and tolerance, causing low battery and Wi-Fi connection problems. It seems this was the case with your thermostat. Replacing the batteries resolved the issue and allowed the thermostat to connect to Wi-Fi.

Please don't hesitate to reply if you have any questions or require further assistance.

Best regards,

Ana