That brand and model will occasionally fall off unless you have certain Zigbee repeaters that they work with. E.g., I have several Ikea TRÅDFRI outlets on my mesh just to keep the 8 Aqara and Xiaomi devices I have connected.
I eventually stopped by buying Aqara/Xiaomi devices because of this annoyance. My Zigbee mesh (about 150 devices) is very stable and I didn't want to pander anymore to known annoying devices.
