Ax_Why I'm network icon vanish
x_a show NIC(network interface card/adapter) status
$ ifconfig -a
x_b modify configuration file change addition eth0 or your NIC
$ vim /etc/network/interfaces
x_c restart networking service
$ /etc/init.d/networking restart
ok, already resolve network connection problem.
But.
Don't have network icon
Bx_Resolve
x_a stop network manager service
$ service network-manager stop
$ service NetworkManager stop // kali 2020.1 new service name
x_b delete networkmanager.state
$ rm /var/lib/NetworkManager/NetworkManager.state
x_c start network manager service
$ service network-manager start
$ service NetworkManager start // kali 2020.1
x_d modify configuration file change false to true
$ vim /etc/NetworkManager/NetworkManager.conf
Successfully!