further information:

From outside network trying to ssh into new computer:

computer-name:~# ssh -vvv xxx.xxx.xxx.xxx
OpenSSH_4.3p2 Debian-9, OpenSSL 0.9.8c 05 Sep 2006
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to xxx.xxx.xxx.xxx [xxx.xxx.xxx.xxx] port 22.
debug1: connect to address xxx.xxx.xxx.xxx port 22: Connection refused
ssh: connect to host xxx.xxx.xxx.xxx port 22: Connection refused

On new computer:

new-computer:/etc# ps -ef|grep sshd
root 3174 1 0 Feb22 ? 00:00:00 /usr/sbin/sshd
root 4807 3174 0 Feb22 ? 00:00:01 sshd: root@pts/3
root 4556 4810 0 06:08 pts/3 00:00:00 grep sshd

new-computer:/etc# netstat -tanpl|grep sshd
tcp6 0 0 :::22 :::* LISTEN 3174/sshd

new-computer:/etc# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination