How would WatchYourLAN know which devices are using randomized MAC addresses?

The second character in a MAC address is always either 2, 6, A, or E if its a randomized address.

Thanks. I didn't know that. Does that correspond to the "Local bit" =1 and "Global bit" = 0 in section 2.1 of the RFC? i.e. bitand(first byte, 3) == 2 https://www.rfc-editor.org/rfc/rfc7042#page-6

FWIW, I don't know if you want to remove randomized addresses since you still want to know that they're connect to the LAN, and devices might connect with a consistent but randomized MAC. However, they should certainly be marked as randomized.

it would be great to be able to mark these devices. Or even have two sections, one with the known online devices and one with the unknown online devices ( same for the offline ). basically this can help to understand - visually - which devices are new ( or use randomized mac addrs ) .