@motorider 

When the connection "breaks" what mode is enabled?  AX only or b/g/n/ax mixed?  It is possible that these devices are not yet updated to work with AX mode enabled.  Even though AX is supposed to be fully backwards compatible there have still been issues.  One thing to you can do to test this theory is try your nest thermostat on 5GHz with A/N/AC/AX mode enabled.  Let us know if it works or not. 

@Carl  Working config shown below. When "Mode" (shown by arrow) is set to "802.11b/g/n/ax mixed" those devices don't work. On "802.11b/g/n mixed" they work. All other setting stay the same. I can *sometimes* get devices to work by dropping encryption level but after rebooting the router devices might still drop off the network. Config below with shutting off AX fixes it. 5GHz devices are all fine with out of the box settings ("802.11b/g/n/ax mixed"). I'm pretty sure this is a bug since I believe they all worked out of the box with the original shipped firmware (unfortunately I don't know which version that was).

I may give the Nest a try when I have a moment, IIRC it didn't have 5GHz (I think it's gen 2 IIRC).

@Carl confirmed, the Nest doesn't have 5Ghz.

@motorider 

Sorry about that I was basing that off my Nest.  It does have 5GHz as well.  I'm am going to engage our engineering team to see if they have any suggestions.  I'd like to avoid replaceing a product if it doesn't actually need to be replaced.  I will respond when i hear back. 

@motorider 

Here is the response from our engineering team:

The latest firmware 1.1.1 Build 200714 does have changes on the wireless module, it adds WPA3 feature, but I checked the screenshot provided by the user, he didn't use WPA3. At present. we can't locate the reason. I have two solutions:

a. This user mentioned that there is no problem with the previous version. We can help the user downgrade back to the previous firmware version to solve the problem, which can fix the user's problem in a short time.

Note: The latest firmware 200714 set limitation on the downgrade, we need to use beta firmware to help customers downgrade. The process is a little complex, we suggest we can schedule a remote session with the user to finish it, If it goes well, the process will be completed in 15 to 30 minutes.

b. If the user is willing to cooperate with us and go further about the problem, please tell me the Email of the user, I will follow up the issue using new Ticket.

My suggestion would be to try option B.  the reason being is that you would likely need to work with support to do a downgrade anyways why not try to resolve the concern on the current firmware.

What I would need you to do is send an email to ussupportteam@tp-link.com.  Include a link to this thread, your name a good phone number and email address they can reach you at and a good 1-2 hour window when you would be available.  Our engineering team is located in China so they would be available during our evenings 5:30 pm Pacific to 6 am Pacific. 

 

@Carl I don't think this is anything wrong with my router or a case for product replacement - it just looks like a firmware/software bug. The hardware seems fine to me. Let me know what the engineers find.

@Carl Sorry I missed that last reply of yours. I see no reason to downgrade now when it works fine as long as I turn off 2.4Ghz ax and I have no devices that would use ax at this time. Please just keep trying to resolve the issue in software for a future release. It appears not to be very difficult to reproduce.