Make sure there are no redundant ifcfg-* scripts in /etc/sysconfig/network-scripts/ directory
[root@rhel7client1 ~]# systemctl restart network
Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "journalctl -xe" for details.
Make sure interfaces configured for automatic IP address have DHCP to assign IP, else change to manual before activating
root@rhel7client1 ~]# nmcli con up enp0s8
Error: Connection activation failed: IP configuration could not be reserved (no available address, timeout, etc.)
[root@rhel7client1 ~]# nmcli con mod enp0s8 ipv4.addresses "192.168.0.20/24"
[root@rhel7client1 ~]# nmcli con mod enp0s8 ipv4.method manual
[root@rhel7client1 ~]# nmcli con up enp0s8
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/11)