During boot of your system and just after the BIOS messages Ubuntu might display a black screen with an error: no video mode activated message. The system boots normally but it is annoying.

GRUB by default hides the boot menu and this message can show up if there is no video mode set. It seems to be a known bug when the hidden option is active. I think you can just dismiss is it with ESC or ignore it as it has no adverse effect.

If you find it annoying you can get rid of it with the following steps.

Activate the menu option in GRUB.

vim /etc/default/grub

Make the following changes. Adjust your timeout to the number of seconds you want the boot menu to be displayed. Values below 5 seconds are difficult to catch.

#GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT_STYLE=menu
GRUB_TIMEOUT=10

Update the changes:

$ sudo update-grub

Reboot and check that the changes have been applied correctly.

Ubuntu Server and Ubuntu Desktop use different network managers. Ubuntu Server uses networkd which doesn’t have a GUI component. So after adding a desktop to Ubuntu Server you won’t be able to see or change the configuration via the GUI by default.

	Ubuntu Desktop	Ubuntu Server
Configuration tool	netplan	netplan
CLI manager	nmcli	networkd
GUI manager	NetworkManager	n/a

For you to be able to see the network settings on the GUI you need to switch from networkd to NetworkManager.

Install NetworkManager:

apt install network-manager network-manager-gnome network-manager-openvpn network-manager-openconnect network-manager-openvpn-gnome

Check which systemd network daemons are active:

systemctl list-unit-files | grep -i network

Disable/stop networkd services:

systemctl disable systemd-networkd.service
systemctl disable networkd-dispatcher.service
systemctl stop systemd-networkd
systemctl stop systemd-networkd.socket
systemctl stop systemd-networkd.service
systemctl stop network-dispatcher.service

Remember that nmcli can be used for CLI NetworkManager control also.

Network interfaces are listed in yaml files in /etc/netplan/

Edit /etc/netplan/50-cloud-init.yaml and edit the line or add a line after the version: 2 entry to be renderer: Networkmanager.

network:
  ethernets:
    eno1:
      dhcp4: true
  version: 2
  renderer: NetworkManager

Check the changes and apply them:

netplan generate
netplan try / netplan apply