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Nest thermostat W5 error: Wi-Fi hardware may have failed
W5 is special: Google says it can indicate a hardware malfunction. Restart and retry Wi-Fi once; if W5 remains, the thermostat may need replacement.
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W5 is special: Google says it can indicate a hardware malfunction. Restart and retry Wi-Fi once; if W5 remains, the thermostat may need replacement.
Check these first
- Confirm the thermostat itself shows W5 in Settings > Network.
- Restart the thermostat.
- Retry the known working Wi-Fi network.
Fix it in this order
- Confirm W5.
- Restart.
- Attempt reconnection once.
- If W5 persists, contact Google Nest with the serial and W5 code for replacement/service options.
Evidence to keep
- Photo of W5
- Serial number
- Restart/reconnect result
Do not make it harder
- Factory resets before confirming the code
- Replacing the router solely because of persistent W5
How you know it is fixed
- Thermostat connects reliably with no W5, or the failed unit is replaced.
If the obvious fix does not work
- If W5 disappears but connectivity remains intermittent, use the general Wi-Fi path instead.
- If the thermostat is offline but does not show W5, do not assume hardware failure.
If this still isn't resolved
- Google Nest Support
Sources for this path
Use these references to confirm provider-, model-, policy-, or jurisdiction-specific details before an irreversible step.
Need the complete context?
This page solves one branch. The parent guide covers the full decision, edge cases, alternatives, and related checks.