Make sure you have consolekit, libpam-ck-connector and policykit-1 installed. Any of those missing has been a source of authentication problems for others. Maybe look at some of the discussions about mate on this forum. I don't know if anyone else has had this problem. (Usual problems are with shutdown/reboot and mounting removable media.)

I checked and all three packages are installed.

Not a problem here. I can get to tty1-6 from the login screen or from the desktop. Say a little more about how and what you installed. Full desktop? Minimal install and then added stuff?

Is there some other key you need to press to get the function keys to work on this laptop?

In the text installer I have chosen Mate Desktop. It came with slim. Afterwards I have installed wdm and lightdm.

All three display managers have the same problem: CTRL-ALT-F1 does not open tty1, instead it restarts the display manager
and goes to the greeter. My laptop has a Fn key between CTRL and ALT. I have tried CTRL-Fn-ALT-F1, CTRL-Fn-F1, Fn-ALT-F1, Fn-F1,
but nothing happens. Only CTRL-ALT-F1 has an effect: it switches to the login screen as already described.

I have another older laptop and a desktop with Devuan Jessie but on them everything works fine.

I have opened a shell on the laptop using ssh. Below is the output of  tail -f /var/log/lightdm/lightdm.log when I press CTRL-ALT-F1.
As you can see, the X server is terminated immediately. Also, there is a ConsoleKit warning that I do not understand.
Maybe some shortcuts are messed up? As far as I can remember, killing the X server should be CTRL-ALT-Backspace.

[+1158.27s] DEBUG: Process 3636 terminated with signal 11
[+1158.27s] DEBUG: DisplayServer x-0: X server stopped
[+1158.27s] DEBUG: Releasing VT 7
[+1158.27s] DEBUG: DisplayServer x-0: Removing X server authority /var/run/lightdm/root/:0
[+1158.27s] DEBUG: Seat: Display server stopped
[+1158.27s] DEBUG: Seat: Stopping session
[+1158.27s] DEBUG: Session pid=3654: Sending SIGTERM
[+1158.27s] DEBUG: Seat: Stopping session
[+1158.27s] DEBUG: Session pid=3683: Sending SIGTERM
[+1158.27s] DEBUG: Seat: Active display server stopped, starting greeter
[+1158.27s] DEBUG: Seat: Creating greeter session
[+1158.27s] DEBUG: Seat: Creating display server of type x
[+1158.27s] DEBUG: Using VT 7
[+1158.27s] DEBUG: Seat: Starting local X display on VT 7
[+1158.27s] DEBUG: DisplayServer x-0: Logging to /var/log/lightdm/x-0.log
[+1158.27s] DEBUG: DisplayServer x-0: Writing X server authority to /var/run/lightdm/root/:0
[+1158.27s] DEBUG: DisplayServer x-0: Launching X Server
[+1158.27s] DEBUG: Launching process 3692: /usr/bin/X :0 -seat seat0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch
[+1158.28s] DEBUG: DisplayServer x-0: Waiting for ready signal from X server :0
[+1158.28s] DEBUG: Session pid=3683: Terminated with signal 15
[+1158.28s] DEBUG: Session: Failed during authentication
[+1158.28s] DEBUG: Seat: Session stopped
[+1158.34s] DEBUG: Session pid=3654: Greeter closed communication channel
[+1158.34s] DEBUG: Session pid=3654: Exited with return value 0
[+1158.34s] DEBUG: Seat: Session stopped
[+1158.34s] DEBUG: Seat: Stopping display server, no sessions require it
[+1158.97s] DEBUG: Got signal 10 from process 3692
[+1158.97s] DEBUG: DisplayServer x-0: Got signal from X server :0
[+1158.97s] DEBUG: DisplayServer x-0: Connecting to XServer :0
[+1158.98s] DEBUG: Seat: Display server ready, starting session authentication
[+1158.98s] DEBUG: Session pid=3711: Started with service 'lightdm-greeter', username 'lightdm'
[+1159.03s] DEBUG: Session pid=3711: Authentication complete with return value 0: Success
[+1159.03s] DEBUG: Seat: Session authenticated, running command
[+1159.03s] DEBUG: Session pid=3711: Running command /usr/sbin/lightdm-gtk-greeter
[+1159.03s] DEBUG: Creating shared data directory /var/lib/lightdm/data/lightdm
[+1159.03s] DEBUG: Session pid=3711: Logging to /var/log/lightdm/x-0-greeter.log
[+1159.08s] DEBUG: Activating VT 7
[+1159.08s] DEBUG: Activating ConsoleKit session 98255d81a70a6f4819439a685a633043-1516645474.422095-851764063
[+1159.08s] WARNING: Error activating ConsoleKit session: GDBus.Error:org.freedesktop.DBus.GLib.UnmappedError.CkVtMonitorError.Code0: Session is already active
[+1159.31s] DEBUG: Session pid=3711: Greeter connected version=1.10.3
[+1159.66s] DEBUG: Session pid=3711: Greeter start authentication
[+1159.66s] DEBUG: Session pid=3739: Started with service 'lightdm', username '(null)'
[+1159.67s] DEBUG: Session pid=3739: Got 1 message(s) from PAM
[+1159.67s] DEBUG: Session pid=3711: Prompt greeter with 1 message(s)

Is there some other key you need to press to get the function keys to work on this laptop?

giorgiob wrote:

Yesterday I performed a fresh install of Devuan Jessie on my ASUS laptop. Everything seemed to go fine but then I noticed that I cannot switch to a console with CTRL-ALT-F{1, 2, 3, 4, 5, 6} from the Slim login. If I try this after I have logged in, the user gets logged and I am brought back to the Slim login.

Is this a known problem or can it be that I have to configure something on my system?

this is very strange. it could be a bug.

could you try : apt-get install wdm

install wdm by default. reboot, and try ctrl f1,....

let us know about this test.

(I note: you know there is a huge bug with /dev/video !! permissions are wrong under devuan for some x11 things. one day someone will find out.)

Thanks for the hint. I tried both wdm and lightdm but they behave in the same way as slim: CTRL-ALT-F1 brings me back to the greeter. This happens even if I am logged in as root. Do I need to change the permissions of /dev/video in some way?

Yesterday I performed a fresh install of Devuan Jessie on my ASUS laptop. Everything seemed to go fine but then I noticed that I cannot switch to a console with CTRL-ALT-F{1, 2, 3, 4, 5, 6} from the Slim login. If I try this after I have logged in, the user gets logged and I am brought back to the Slim login.

Is this a known problem or can it be that I have to configure something on my system?

this is very strange. it could be a bug.

could you try : apt-get install wdm

install wdm by default. reboot, and try ctrl f1,....

let us know about this test.

(I note: you know there is a huge bug with /dev/video !! permissions are wrong under devuan for some x11 things. one day someone will find out.)

Is this a known problem or can it be that I have to configure something on my system?