Problem with multiple monitors

[Alexander Ploumistos]

OK, first things first. This is a quick but relatively comprehensive
overview of ttys, vts etc.:
https://mostlylinux.wordpress.com/troubleshooting/ttysessions/

In my rhbz post, I wrote that when your system is set to boot into
graphical mode, when you kill the wayland server (or gdm I suppose),
gdm spawns a new login manager session, while the previous Xorg
instance with your desktop environment is left running. So you can
keep killing wayland (or perhaps gdm?), getting to a new login prompt
and starting new X sessions, until you run out of ttys. I believe that
is what you are experiencing, i.e. when you dock the laptop, gdm hangs
up and respawns.

You can check with something like
ps ax | grep -E "X|wayland"

and see what is running on which tty.

For example, if you get something similar to

1812 tty2     Sl+    0:35 /usr/libexec/Xorg vt2 -displayfd 3 -auth
/run/user/1000/gdm/Xauthority -nolisten tcp -background none -noreset
-keeptty -verbose 3
3016 tty4     Sl+    0:22 /usr/libexec/Xorg vt4 -displayfd 3 -auth
/run/user/1000/gdm/Xauthority -nolisten tcp -background none -noreset
-keeptty -verbose 3

you can tell that you have one graphical session running on tty2 and
another one on tty4 and you can switch between them with Ctrl+Alt+F4
and Ctrl+Alt+F2.

Perhaps someone knowledgeable can give a more accurate description.