Getting to the bottom of my failed British General (BG) sockets

[Crimliar]

Rather than use smart adapters, I've used BG Smart wall sockets in a couple of places around the home - mostly where protrusion was an issue. These sockets form their own network with a single socket (it can be any socket, they're identical) being the bridge between them and the main WiFi network. Over a period of time though, I found these to become increasingly unreliable. The oddest part of that unreliability being that at times there seemed to be no "bridge" socket on the network, but remote control would still mostly work. Last weekend I removed the last of my BG smart wall sockets. So I was a little surprised to see in the overnight router logs more than 1,000 failed attempts by, according to the MAC address, what is apparently a BG smart wall socket.
Just to be safe, I've blocked the MAC address. Everything here is working, so I'm assuming this is a device in one of my neighbours homes (-77dBm). I'm wracking my brains to think if I've set anything up for someone else, but among my direct neighbours the only devices I can think of are alarm systems with some wireless (433/866MHz which is the band I believe the BG stuff uses to communicate between devices on too) components, but I'd definitely never have set any of these using my WiFi!
The device whatever it may be, seems to have never successfully connected to my network, so I'm left trying to figure out exactly what may have happened. I don't want to go down the conspiracy rabbit hole, but I'm leaning towards a software issue on a device owned by a neighbour - if this is another Sky-Mini issue I'll scream!

So, any non-conspiratorial ideas. I've thought about setting up a honey-pot/tar-pit but if this is an innocent issue that could be a lot of work, and I'm lazy like that! *BG Luceo support is useless!

 

[Digilog]

Looking at them. These use the older 2.4 Ghz wireless that was used in wifi cameras. They have issues with routers that have 5Ghz+2.4Ghz coexistence.

What you should do is get a separate access point (or cheap router in AP mode) for them and configure it with 2.4GHz and connect all the sockets to it.

I wouldn't worry about the rouge MAC trying to connect too much. This is a symptom of someone not setting it up correctly and their socket is going into 'discovery' mode because it lost its login credentials.

Also, disable WPS in the router. These normally use an app to set up the wireless connection by connecting to them by blue tooth and the phone app transfers the wifi credentials to the socket. So make sure the phone is connected to that 2.4Ghz router.

 

[Crimliar]

The upgrade to the latest firmware allowed me to FINALLY identify the rogue device! It appears to be an oddity with our smart washing machine in certain scenarios (in normal use, it's fine/fantastic). Identifying it has allowed it to be easily fixed!