I noticed somehow after installing Ubuntu Server 16.04 LTS that when booting the system, the monitor does not display the login and password entry line, and every time the black screen, the system does not respond to keystrokes, and the system has booted and you can connect to it via SSH.
As it turned out, the login and password input window is displayed after pressing the Ctrl+Alt+F1 key combinations.
Strange however, because on versions of Ubuntu Server 14.04 LTS and below it was displayed immediately.