• Veyon version: 4.10.2
• Operating System: Windows 11 25H2
• Role: Teacher PC running Veyon Master
• Multiple schools and teachers affected

Description

While Veyon Master is running, keyboard modifier keys (especially CTRL and sometimes SHIFT) stop working intermittently.

The issue is easy to notice when using common shortcuts such as:

• CTRL + C
• CTRL + V

Instead of executing the shortcut, the application sometimes receives only the character key.

Examples:

• CTRL + C results in "c" being typed.
• CTRL + V results in "v" being typed.

The behavior is random. Sometimes the shortcut works correctly and sometimes it does not.

Observations

• The problem occurs only while Veyon Master is running.
• If Veyon Master is completely closed, the problem disappears immediately.
• The problem still occurs even when Veyon Master is minimized.
• No errors are recorded in Windows Event Viewer.
• Multiple teachers from different schools have reported the same behavior.
• Replacing the physical keyboard does not solve the issue.
• Removing the Interception Driver does not solve the issue.

Additional Testing

Using the Windows On-Screen Keyboard (OSK):

• When the issue occurs, the CTRL key is correctly shown as pressed in OSK.
• However, applications sometimes receive only the "C" or "V" key and ignore the CTRL modifier.

This suggests that Windows correctly receives the modifier key state, but applications intermittently lose the CTRL modifier while Veyon is running.

Other Symptoms

Occasional mouse input anomalies have also been observed during classroom management sessions.

Expected Behavior

Keyboard shortcuts involving CTRL, SHIFT and other modifier keys should always work correctly while Veyon Master is running.

Actual Behavior

Modifier keys are intermittently ignored, causing shortcuts to fail and resulting in normal character input instead.

Could this be related to global keyboard hooks, input event handling, Qt, or a compatibility issue with recent Windows 11 versions?