OK, that was a problem with my comprehension of veyon. The port 11400 is listening on master only when you start demo mode. So i found my error, it was in access control on the master. The user i which i was tested was not authorized. I wa able to supervise the clients but only the demo mode was bugging because of access control. Thanks to lyc_appert for his help

@Badbug Yes, restarting the Master machine solve the problem (for a while), but I don't want to restart my Master PC every day, because it's like a server machine in our network

Hi, Have you tried with the fullpath name of the program ? If the program is in the environnement PATH, it should work. I tested with "notepad" and it launch on the client. So you can try with notepad to see if it work also.

Bonjour Là : https://docs.veyon.io/fr/latest/admin/index.html

Hi, you can use host names instead of ip adress.

can you please elaborate more about your situation? did u installed the latest version? what operating system the master and the clients are using and what you tried to do that made the error appear?

Yes it is, Reproductile on several pc of brand and different generation

First of all: 4.3.0 is the most recent version while 4.1.2 is a very old version released more than a year ago And yes, usually you should update both master and client computers. Use silent installation options to automate this task easily: https://docs.veyon.io/en/latest/admin/installation.html#automated-silent-installation

Unfortunately Veyon Master is not capable of filtering computers based on access control rules on the client computers. The reason for this is that the local state of the individual computers (which user is logged on etc.) is not known to Veyon Master so we can't reliably determine whether a certain computer can actually be accessed or not.

You can try to set up https://docs.veyon.io/en/latest/admin/access-control-rules.html and play with the conditions regarding computer locations. This way you can prevent users easily from accessing computers at a different location (room).

Problem solved. Username is Student with no password. A password is not required when using key file authentication. Computer name is used to identify machine.