rapfenhttps://askubuntu.com/questions/906636/ethernet-adapter-was-disable-on-ubuntu-17-04
Here is how to fix this problem.
Edit file /usr/lib/NetworkManager/conf.d/10-globally-managed-devices.conf and change it's content from :
[keyfile]
unmanaged-devices=*,except:type:wifi,except:type:wwan
To :
[keyfile]
unmanaged-devices=*,except:type:ethernet,except:type:wifi,except:type:wwan
And then run :
sudo service network-manager restart
That's all.
Ez lenne az.