There are 2 ways to Start, Stop, Restart and also show Status of the network services on a CentOS 8 or RHEL 8 Linux system.
1. Using NetworkManager.service:
#sudo systemctl start NetworkManager.services
#sudo systemctl stop NetworkManager.service
#sudo systemctl restart NetworkManager.service
#sudo systemctl status NetworkManager.service
2. Using nmcli:
ref; nmcli is a command-line tool for controlling NetworkManager and reporting network status.
Alert: Do not run the "nmcli networking off" command if you are connected thru ssh based session, then you will end up getting ‘network connectivity lost'.
#sudo nmcli networking on
#sudo nmcli networking off
#sudo nmcli general status or #sudo nmcli device status