Isc dhcp service start on boot as root

I’m using “isc-dhcp-server” on my osmc raspberry which is conneted via ethernet. Via an usb to ethernet adapter I enable my tv to connect to the internet too.
This isc-dhcp-server service is working fine if I start it manually via sudo after booting up… “sudo service isc-dhcp-server start”.
However, I could not find a way yet to start this service automatically via root… not via rc.local, not via cron and via systemd I don’t know how to execute it as root.
Any help is much appreciated!
Thanks, pakko

Try sudo systemctl enable isc-dhcp-server and reboot.