How install Graphical User Interface (GUI) on Debian 11

login to debian machine;

su
[enter root password and press enter]
apt update
apt upgrade -y

Install GNOME desktop environment

apt install task-gnome-desktop

Once the GNOME desktop installation has been completed, the next step is to assign the graphical runlevel.

Change the default boot to graphical runlevel by executing the below command to ensure that the next system boot goes to GUI.

systemctl set-default graphical.target

By default, root user login is disabled via GNOME Display Manager (GDM). For enabling root access, follow the below steps:

Log in to the server through SSH and edit the GDM configuration file /etc/pam.d/gdm-password using any editor of choice.

nano /etc/pam.d/gdm-password

Locate the line that reads as below:

auth  required  pam_succeed_if.so user != root quiet_success

Remove/comment out this line by prefixing # and then save and close the editor.

#auth  required  pam_succeed_if.so user != root quiet_success

Reboot the Debian server with the reboot command

Once the reboot is completed, access the server through Console option via LayerPanel and the GUI interface will be ready to be used. Log in to the server using the user account credentials to start managing the Debian server through GUI.