FIX: Netatmo Thermostat not connecting after Legrand Home + Control Migration (Don't listen to Support saying "buy a new one"!)
Hi everyone,
After 1 month conversation with the Netatmo support team I wanted to share a success story because Netatmo/Legrand support almost convinced me to throw away perfectly fine hardware.
The Problem: After the forced migration from the Netatmo Energy App to the Legrand Home + Control App, my Relay updated its firmware. After that, the Relay was visible to support and connected to the cloud, but it refused to pair with the Thermostat. I couldn't even get to the step where the code is displayed.
The official Netatmo support told me my hardware was too old/incompatible and that I should "just buy a new thermostat," even though it worked perfectly 5 minutes before the update.
The Solution (that actually worked): Don't give up! Here is the "Hard Reset / Deep Sync" method that fixed it for me:
- Drain the Thermostat: Remove the batteries from the Thermostat and leave it without power for at least 10 minutes to fully drain the capacitors.
- Unplug the Relay: Unplug the Relay (or turn off the boiler power) during this time.
- The "5-Blink" Factory Reset:
- Plug the Relay back in.
- Hold the button on the Relay for about 20 seconds.
- It will blink slowly for the first 15 seconds. Keep holding it!
- Wait until the LED stops blinking and then flashes 5 times rapidly. This is the true factory reset that clears old pairing IDs.
- The Pairing Process:
- Put the batteries back into the Thermostat.
- Crucial: Immediately press the Thermostat display/button for 15-20 seconds to trigger its manual pairing mode before you start the process in the App.
- Start the "Add a product" process in the Legrand Home + Control App.
For me, the code finally appeared on the display, and the connection was successful.
Conclusion: It seems the new firmware creates a "pairing lock" or uses a different encryption that requires a complete wipe of the Relay's memory (the 5-blink reset). If support tells you your hardware is dead after a software update, don't believe them. Try the deep reset first!
Hope this helps someone else save their "old" hardware from the bin.