ubuntu 18.04, nm(Network Manager) is not able to manage network devices [duplicate]

Solution 1:

I had this happen with an installation of Ubuntu Server 18.04 (Which uses netplan) and then adding a desktop window manager GUI (in our case, xubuntu-core^).

No Manner of re-configuring or nmcli would make these devices managed.

The solutions you tried were close, we found that if you follow the answer located here: Ethernet device not managed and note that the location of the 10-globally-managed-devices.conf is in the folder /user/lib/ you will be able to active those network devices by blanking the 10-globally-managed-devices.conf file with:

sudo mv /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf  /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf_orig

and

sudo touch /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf

And restarting network-manager or rebooting.