1、systemctl status NetworkManager
2、systemctl restart NetworkManager
或者systemctl stop NetworkManager/systemctl start NetworkManager
3、开机自启动
systemctl enable NetworkManager
4、如果版本不匹配yum -y update会升级NetworkManager的（包含nmcli）
rpm -qf /usr/bin/nmcli
NetworkManager-1.8.0-9.el7.x86_64
nmcli -v
nmcli tool, version 1.8.0-9.el7