Recently I set up a freeradius server to work with DUO MFA for a remote access VPN. Everything worked but I had to reboot the server and I noticed the freeradius server service was not running after the reboot.
Please note you can replace the freeradius service with the name of the service with which you are working.
To enable the service to automatically start I ran the following command-
systemctl enable freeradius.service
To disable a service from automatically starting you can run the following command
systemctl unmask freeradius.service