[systemd-devel] hanging reboot

[Hajo Locke]

Hello list,

sometimes i have problems rebooting some machine. i think in that cases 
shutting down some services fails and machine stays somewhere between 
life and death.
Unfortunately my ssh window closes at first and no reconnect is 
possible, it only tells "Connection refused".
If this happens, then i have to do a call to someone who works in 
datacenter and resets my machine by hand.
I would like to keep sshd alive as long as possible to reconnect and fix 
this by hand.
How can i achive this?
System is Ubuntu 16.04 with systemd 229-4ubuntu16
I googled some similiar questions and tried but without success.
What could i do?

Thanks,
Hajo