The unmanaged network issue occurs when on previously GUI less Debian system the GUI and the Network Manager is installed. The reason is that Network Manager has been denied access to network management.
This is a companion discussion topic for the original entry at https://linuxconfig.org/unmanaged-network-solution-on-debian-linux
As you will see below, the unmanaged network issue can easily be fixed by editing the main NetworkManager's configuration file /etc/NetworkManager/NetworkManager.conf.
This is a companion discussion topic for the original entry at https://linuxconfig.org/unmanaged-network-solution-on-debian-linux