now I know a bit more. First I mixed things up: I want to use gdm NOT lightdm due to the fact that with lightdm suspend and lock screen do not work (no idea why). Sorry that I did mix that up. So after I did what you said, I reentered all the commands but I switched lightdm with gdm. I couldn’t uninstall lightdm but I were able to disable it. So now I am using gdm and everyhting works.
What I did before was disable password login for gdm, because I already have full disk encryption so it wasn’t necasarry in my eyes. I read through the Archwiki again and there is said:
If you want to bypass the password prompt in GDM then simply add the following line on the first line of /etc/pam.d/gdm-password:
auth sufficient pam_succeed_if.so user ingroup nopasswdlogin
Then, add the group nopasswdlogin to your system. See Groups for group descriptions and group management commands.
Now, add your user to the nopasswdlogin group and you will only have to click on your username to login.
Do not do this for a root account.
You won't be able to change your session type at login with GDM anymore. If you want to change your default session type, you will first need to remove your user from the nopasswdlogin group.
Read the warning: I can’t change the session type. I have no idea what the session type is, but I guess (didnd’t test it again) this prevented my pc from switching the user (session type?) or seeing the gdm screen. Thats the only reason I can think off.
So for now I have to reenter my password at the login once I start the pc, but therefore the bug is gone. I don’t know if “the bug” comes back when I enable passwordless login. For now I’ll let the system rest.
Another question: Any idea, why suspend does not work with lightdm but with gdm? After I advice my pc to suspend with lightdm I just see a blank console with a “_” blinking and py pc doesn’t respond anymore.
karasu, thanks for all your time, I really appreciate your work and thanks for this great Operating System, I love it!