<snip> Does anyone have any idea why systemd wants to stop ssh after it has started? After I run:
yup. I have updated to "reload" instead of "restart" - will see what happens when I rebootSounds like https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=756547 Caused by the ifupdown hook /etc/network/if-up.d/openssh-server rapidly restarting the ssh service (if you have multiple interfaces) in a short time frame.
Cheers Iain