Thanks for this. I have struggled to find devices on my network in the past, and eventually resorted to using nmap (which I used to use at work years ago).

I was not aware of arp-scan, and have just installed it. It's very much more helpful when searching for that new Pi just added to the network.

I'd not noticed before that "Raspberry Pi Foundation" had become "Raspberry Pi Trading Ltd" apparently with the arrival of the Pi 4, and that the MAC address base had changed then too.

Dave