Solved - application MagicInfo and his uvnc modul made the problem. After killing everything run!

@Prakash-K i'm having the same issue.. Please update once you solve this issue.

@lcrosier Hi,
I have this issue starting from Veyon 4.7.5.
Hitting the "F5" key on the master PC helps to make all clients visible again.
The only temporary solution for me was to roll back the teacher PC to Veyon version 4.7.4, leaving the student PCs with Veyon 4.7.5.
I hope this helps.

Have a good day.
Carlo.

@DCteacher
You are very welcome!
So it was the public key, good to know.
I'm happy you have solved the issue!

Have a good day!
Carlo

Hello,

Thank you for your attention. The options you mentioned are already configured, I researched a little more and found this topic that solved the problem, https://github.com/veyon/veyon/issues/146#issuecomment-342851916

Thanks again.

@jesse26j I downloaded it from the veyon website, not from github. It says version 4.7.4.0 in Windows.

@darrellsimone The documentation should be read first: https://docs.veyon.io/en/latest/admin/installation.html#installation-on-a-linux-computer

The teacher machine needs veyon configurator, the client machines only need veyon master.

In principle, you can also access a machine on an external network, although I haven't tried it yet, but you have to enable Veyon on the firewall. If something doesn't work, feel free to ask, I'm happy to help if I can.

@Luigi-Capp I have fixed it with the command "sudo apt-get -f install /home/luigicapp/Scaricati/Temp/veyon_4.7.5.0-ubuntu.jammy_amd64.deb"
Luigi Cappellazzo

Are you using the latest version on both teacher and student computers?

A typical mistake is that Veyon add-ons are not installed on student computers. Also make sure to configure the Internet access blocking mechanism client-side. Is the Windows Firewall enabled on student computers? If not, please enable it and don't set any group policy which prevents applications from changing the firewall configuration.

This can be easily done with PSTools from Microsoft and a batch script or PowerShell.
I use the following to manually remotely install veyon and the security keys when the GPO installer doesn't work for any reason.
You can replace line 1 with a call to a list of computers rather than specifying a single computer if that fits your needs better.

SET /p computer="enter computername:" XCOPY "\\networklocation\veyon-4.7.5.0-win64-setup.exe" "\\%computer%\C$\" /e /h /y XCOPY "\\networklocation\UserConfig.json" "\\%computer%\C$\" /e /h /y XCOPY "\\networklocation\veyon\Veyon\*.*" "\\%computer%\C$\ProgramData\Veyon\" /e /h /y timeout /t 5 CD "C:\PSTools\" psexec64 \\%computer% C:\veyon-4.7.5.0-win64-setup.exe /S /ApplyConfig=C:\UserConfig.json /NoMaster