Aqara / Xiaomi Smart Plug will not connect to CC2531

I have several Aqara sensors (door, temperature, vibration) connected to my Home Assistant setup via a CC2531, but a couple are juuust out of range of my controller, so I bought a smart plug to extend the range. I followed the instructions at https://www.zigbee2mqtt.io/devices/ZNCZ02LM.html to get it connected to my setup, but no matter what I try the plug does not connect to the Zigbee network.

I have confirmed that it is a Zigbee (and not Wifi) plug, I’ve checked the zigbee2mqtt logs (nothing appears, not even an “interview failed”), I’ve moved my CC2531 so that the external aerial is literally resting on the smart plug, I’ve tried over a dozen times to pair the plug and nothing works. When I hold the button down the LED flashes blue as expected, but after ~30 seconds it stops and … nothing.

I wonder if I’ve just got a duff plug, or if I’m missing something?

I have a bunch of these connected to my CC2531, they do not make good repeaters. I found my zigbee network pretty unreliable until I added a bunch of ikea globes.

You could try holding the button down whilst plugging it in / turning the power on.