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Hardware Problems

Pitfalls - Power LAN

To improve WLAN reception throughout the house I installed a WLAN router in the kitchen and connected it to a power LAN adapter. That adapter is plugged into the wall, and offers a power plug that can be used to support other devices. So I plugged in the fridge. While you may think "aha, the fridge caused electric noise that interfered with the setup" this is not where the story is headed.

Everything was working fine until sometimes it wasn't. IoT devices would connect to the WLAN router but would not get through to the MQTT broker. I could not reach the router of the power LAN either. Resetting the WLAN router and/ or unplugging the power LAN adapter would make things work again. But why would they stop in the first place?

It turns out (after Reading The Fine Manual) that the power LAN adapter has a power saving feature mode that gets triggered by two things:

  • no network traffic for a long time
  • something plugged into the adapter (like, your desktop computer or laptop) stops using power because it was turned off

Now, a fridge does not consume power the whole time but switches itself off (not cooling) and on (cooling) every now and then. Of course, the adapter should leave sleep mode when conditions change, but for whatever reason that did not happen. Maybe the WLAN router went to sleep as well when it felt disconnected?

Problem is, the sleep mode can not be turned off. In the end I resorted to not plugging in anything into the power LAN adapter (other then the network cable to the WLAN router, of course :-P), and things worked happily ever after.

Hardware Problems