Oops! Just remembered 192.168.100.1 is the cable router on my network so that won't work.
"nmap -sT 192.168.10.0/24" shows it.
Nmap scan report for FriendlyELEC.localdomain (192.168.10.219)
Host is up (0.00052s latency).
Not shown: 999 closed ports
PORT STATE SERVICE
22/tcp open ssh
MAC Address: 9A:22:B9:A4:C3:A2 (Unknown)
ssh login successful.