Screen freezes on client PCs although users are actively working (Veyon, Windows, LAN)

[diboine]

Hello,

We are using Veyon in a training environment with the following setup :

• list item3 training rooms
  Each room has :
• 1 master PC
• 8 client PCs

All PCs:

• Windows 11 25H2 (same version and updates)
• Same hardware model (Dell Optiplex)
• Connected via wired Ethernet LAN
• Same Veyon version installed everywhere
• No bandwidth or network latency issues

The system generally works fine, however we regularly experience the following problem :

• When viewing or controlling a client PC from the master PC, the displayed image sometimes freezes.
  On the client side, the trainee continues to work normally (switching windows, opening applications, changing screens), but on the master PC the image remains frozen and does not update.

Additional observations :

• Disconnecting and reconnecting to the client don't fixes the issue
• Switching to another client and back also sometimes refreshes the image

The issue happens randomly, not on a specific PC

Our environment :

• Wired Ethernet only (no Wi-Fi)
• Same subnet
• No firewall filtering between master and clients
• No performance issues on the PCs themselves

We suspect this could be related to:

• Screen capture / mirroring method
• Hardware acceleration (GPU)
• or a known issue with Windows screen updates

Questions :

• Which access / capture method is currently recommended on Windows to avoid frozen screens?
• Are there known issues with hardware acceleration (browsers, GPU drivers)?
• Are there specific settings we should check in Veyon Configurator on client PCs?
• Any guidance or best practices would be greatly appreciated.

Thank you in advance.

Jean-François