Network scripts have been deprecated in RHEL 8. You need to use NetworkManager via the nmcli command. The default RHEL 8 comes with a new version of the ifup and ifdown scripts which calls nmcli. With RHEl 8 you must use NetworkManager tools and applications to configure networking. nmcli is a command-line tool which enables users and scripts to interact with NetworkManager. It must be used on servers where GUI not installed by default.