After boot go automatically to graphical login screen

Solution 1:

I would suggest to (re)install special Lubuntu Desktop task package by

sudo apt-get install --reinstall lubuntu-desktop^

In the above command note ^ at the end, it is task. It will install all the packages which Lubuntu installation has out the box.

Then reboot.

Solution 2:

I would try to install gdm3, because it is robust and works with practically everything. Then, choose it as the default display manager.

sudo apt install gdm3 && sudo dpkg-reconfigure gdm3

the command will install gdm3 and then bring up a screen to choose a default display manager. Please choose gdm3

Reboot, and you should get a gui login screen.

You can do it! I have faith in you!