Well, glad I posted. It was in fact me typing 255 instead of 225. I had never thought about it before but those two numbers look a lot alike. I can't believe the trouble I went through trying different systems etc... All because of misreading a single number in the instructions. May others find this ...

So tried from windows 10 (direct ethernet and via Switch ) also tried via Linux.

With arp - a I get the following output:

config.invisigig.com (192.168.255.1) at {mac address removed} [ether] on eth0

So the Invisigig appears to be showing up. But it isn't responding to anything.

If I try to ...