Sorry for the late repply... Disabling "fast startup" did the trick for me. The replacing of dash with colons didn't seem a good idea, cause for the Lenovo's it worked like that. Only the Dell's were the reluctant ones, so it seemed to be a station configuration problem.

@lmoellendorf Can you try passing -DWITH_PCH=OFF to CMake? Which version of CMake are you using?

@PowerBauer What operating system? Key authentication? Do you assign it by hostname or IP address? If you are using key authentication, have you set two keys on the master that you want to control, and only the public key on the master? Try to set it up based on that, that's what I looked at first. link text

@Roux-Guillaume Bonjour première chose il faudrait installer que le client sur les postes élèves et le master sur le poste prof.. Est-ce le cas ? Fred

Hello, I have several teaching rooms with two master computers in operation. It is important that each master computer needs its own private key. I.e. the students' computers each get a public key of Master 1 and Master 2. Master 1 then has its own private key, Master 2 too. A private key for both masters does not work.

@fred Thanks Fred, exactly as you said, updated Veyon service to 4.7.4 and they all appeared. Much appreciated, Andy