Nest thermostat: W3 or W4: Failed to connect (no IP address or no internet)
Failed to connect. With W3 your router is not giving the thermostat a network IP address; with W4 the thermostat is connected to your wireless network but not to the internet.
Applies to: All Nest thermostats. What you see: a code and words.
Codes this page covers: W3 W4.
What Google says to do
- Google points to its “Failed to connect” troubleshooting article for both codes.
The maker puts this down to Wi-Fi or the network. If the problem is the router itself, its own lights are explained on the router and broadband hub lights page.
Source
Google’s own help page, read on the date shown.
- Google Nest Help: Troubleshoot Nest thermostat help codes — Nest Learning Thermostat (1st to 4th gen), Nest Thermostat E and Nest Thermostat; H codes only where a Heat Link is installed. support.google.com Checked 2026-09-29.