Nest Learning Thermostat (4th gen) will not complete setup or pairing

Look at the screen. The Learning Thermostat (4th gen) has a 2.7-inch circular display at 600 x 600 pixels; the Nest Thermostat has a 2.4-inch rectangular 240 x 320 panel behind a mirrored lens. That is the fastest reliable check, and it matters because the two have genuinely different wiring capabilities.

No — it uses a built-in rechargeable lithium battery charged from the HVAC wiring, not the 2 AAA alkaline cells used by the Nest Thermostat. So a low-power symptom on this model is a wiring or charging investigation, and swapping batteries is not a step that exists here.

Google states it is designed to work with or without one, using its Power Sharing technology, and that in fewer than 1% of cases a C wire or a Nest Power Connector may be needed to guarantee sufficient power in all conditions. So the answer is normally no, with a small and specifically acknowledged exception.

Up to 3 stages of heating (W1, W2, W3) and 3 of cooling (Y1, Y2, Y3), plus heat pump up to 3 stages with 1 or 2 stages of auxiliary or emergency heat. That is substantially more than the Nest Thermostat, which handles one stage of each plus a second stage of either — the main reason to choose this model on a complex system.

Watch the connector limits. Google states the * connector accepts only ONE of W3, Y3, G3, E, HUM or DEHUM, and the AQ+/AQ- connectors accept only Y3 or 1-wire or 2-wire VENT, HUM or DEHUM. On a system needing several of those, this constraint decides the installation before anything else.

Yes — 802.11n on both 2.4 GHz and 5 GHz.

It uses a Soli radar sensor for Motion Sense rather than a passive infrared detector. Radar responds differently to approach and to movement behind objects, which is why its presence behaviour does not match the plain motion sensor in the Nest Thermostat.

A failure that lands consistently on one step is describing a real constraint, not a glitch. Failures at the network step point at band or credentials; failures at the account step point at ownership or region; failures partway through the transfer point at power. A truly random failure looks random — it moves.

Usually not. A factory reset clears settings held on the device. Ownership is held in the provider's account system, and only the previous owner or the manufacturer's support team can release it. This is deliberate — it is what makes a stolen device useless.

Far more often it is a phone permission. Bluetooth and Local Network access are both required to discover a device during setup, and a denied Local Network grant on iOS produces exactly the symptom of absent hardware. Check the per-app permission screen before concluding anything about the device.

Not for Nest Learning Thermostat (4th gen), which joins on 2.4 GHz. The phone may be on 5 GHz while both bands share a network name, and the setup app cannot always tell you that is the problem. Join the phone to 2.4 GHz explicitly for setup.

No. The constraint applies to setup, when credentials are handed over. Once joined, the device stays on the band it supports. Splitting the network temporarily is a diagnostic shortcut, not a permanent requirement.

Guest networks normally enable client isolation, which prevents the phone and the device from seeing each other. Setup may appear to complete and the device then never becomes controllable. Use the main network.

Not on any network that requires accepting terms in a browser. The device has no browser and cannot complete a captive portal sign-in. Networks that register devices by MAC address may work if the administrator registers it first.

Matter setup codes are consumed per commissioning attempt, and a partially completed attempt can use one. Generate a fresh code from the device's own app rather than rescanning the printed label.

Next to the router, then move it. Setup transfers credentials over the weakest link in the chain and fails ambiguously at marginal signal. Confirming it works at close range separates a setup problem from a placement problem.

Once, cleanly, after each change you make. Repeated rapid attempts trigger claim rate limits on several platforms, and after that the error message describes the rate limit rather than your original problem — which is how people end up chasing a fault that no longer exists.

That is a power symptom. A thermostat drawing from the heating circuit rather than a dedicated common wire can hold enough charge for the display and not enough for sustained radio use. Check whether a C wire is landed, and read the thermostat's own voltage diagnostic rather than judging by the screen being lit.

That splits cleanly: control it once on the home network, then once from cellular with Wi-Fi off. Local control working and remote failing is an account or provider-service issue. Neither working is a network join that did not actually complete.

Only with the seller present to remove it from their account, or with proof of purchase for a support release. Cloud ownership survives factory resets by design, and a locked device cannot be recovered by any sequence of button presses.

It can. Setup paths change between app releases more often than device firmware does, and an outdated app can fail against a newer device that shipped with newer firmware. Update the app before the fourth attempt, not after the fortieth.

No. It is scoped to GA05551. Google Nest/Home device; Matter/Thread role, wired/battery power, subscription and Google Home migration vary.

Record the complete model identifier, exact message or indicator, software/firmware where visible, the operating stage and what still works.

A reset can erase accounts, networks, maps, schedules or preferences without distinguishing setup, pairing. The ordered checks preserve that evidence.

Keep setup codes private and do not reset shared security devices casually.