Linux/Ubuntu 18

Missing rc.local
Not created by default, but can be added.

Make sure to create with:
 * 1) !/bin/bash

and chmod +x /etc/rc.local

Check status: systemctl status rc-local

Run: systemctl restart rc-local

Ref
 * 
 * 

systemd
Systemd Unit Files Locations Directory - Description:
 * /usr/lib/systemd/system/: Systemd unit files distributed with installed RPM packages.
 * /run/systemd/system/: Systemd unit files created at run time. This directory takes precedence over the directory with installed service unit files.
 * /etc/systemd/system/: Systemd unit files created by systemctl enable as well as unit files added for extending a service. This directory takes precedence over the directory with runtime unit files.

10.6. Creating and Modifying systemd Unit Files - Red Hat Customer Portal - https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/sect-managing_services_with_systemd-unit_files

/etc/systemd/system/

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/chap-Managing_Services_with_systemd#tabl-Managing_Services_with_systemd-Introduction-Units-Locations