Oh, and I just now saw this:
SSHDConfig: Error: command ['/usr/sbin/sshd', '-T'] failed with exit code 255:
Missing privilege separation directory: /var/run/sshd
That directory is created on startup, unless something else happened. Maybe
your /var/run symlink is busted?
Please check:
ls -lad
Thanks for filing this bug in Ubuntu.
This is the error that was logged:
Setting up openssh-server (1:7.2p2-4ubuntu2.8) ...
Unsafe symlinks encountered in /var/run/sshd, refusing.
Job for ssh.service failed because the control process exited with error code.
See "systemctl status ssh.service"
