For some reason we have installed the system from mini.iso. Then we have install MATE desktop into the system by one of the commands:
sudo apt-get install ubuntu-mate-core^
sudo apt-get install ubuntu-mate-desktop^
Then on first boot of installed MATE desktop we can see that NetworkManager is unable to manage the network interfaces and shows that at least Ehernet Network — device not managed.
This should be fixed. And below is the method to fix it.
With the help of this Q&A from AskUbuntu we need to do the following:
Remove systemd-networkd renderer:
sudo rm /etc/netplan/01-netcfg.yaml
Restore NetworkManager renderer:
cat <<EOF | sudo tee /etc/netplan/01-network-manager-all.yaml
# Let NetworkManager manage all devices on this system
Apply netplan configuration with:
sudo netplan apply
sudo service network-manager restart
Optionally restore contents of
cat <<EOF | sudo tee /etc/network/interfaces
# interfaces(5) file used by ifup(8) and ifdown(8)
iface lo inet loopback
And then reboot.
The resulting system will use NetworkManager as it intended to be when MATE was installed from official full ISO.