It wasn't quite that simple.
At first I got an error of "no path to host"
Checked the router's settings- all good
Then I got an error message of:
turns out that sshd has to be restarted on both machines
then the connection was established, but
"read from socket failed: connection reset by peer"
this was solved by the command
ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key
issued as root from /etc/ssh/ to regenerate valid keys
since then I've been able to connect. Thanks again.