Ah yes, the new menu item:
use only Ping for up and down tripped me up at first as I did not spot this - the option above:
use Ping up and down does not appear to work whether the subnet is defined (fingscan>Configure) to cover the external subnet or not.
I am guessing that it is best to define the subnet (fingscan>Configure) to just cover the same subnet that the Mac running Indigo is installed on, so that fing itself does not bother trying to access hosts outside it's broadcast scope - is this correct? This is how mine is currently set, and the devices in other subnets outside my Mac Indigo PC are set to:
use only Ping for up and down.
Since devices in other subnets have to traverse some sort of router, fingscan would not be able to use (or determine) the mac address, so I'm guessing this field:
(overwrite) MAC number on the new IP device menu is not needed for Ping only devices?
So pleased this is working