This is how to get serial port console working on a Ubuntu 16.04 (or any systemd based OS) and how to access it with idrac/ssh.
To get serial port working on a running system:
To get serial console during boot up, including the grub menu:
Go ahead and edit
GRUB_CMDLINE_LINUX_DEFAULT="splash quiet" GRUB_CMDLINE_LINUX="console=tty0" GRUB_TERMINAL="console serial" # also, it takes so long to boot a server, adding 10 # second to the grub menu is more good than harm GRUB_TIMEOUT=10
Access it via idrac
ssh <idrac-ip> console com2