Demo mode not working (everything else is fine)

[tatanas]

Hi,

I've got a problem with demo mode. When the teacher wants to share his screen with demo mode, the window's demo open on students hosts but it keeps black and nothing happens.
Everything else is working fine.

All computers are on Windows 10 pro 64bits 2004 and Veyon 4.6 (the problem appears on 4.5 too).
We use an external vnc (Ultravnc 1.2.1.6) on default port 5900.

Here is the debug log :

2021-10-18T13:47:29.786: [DEBUG] PluginManager::loadPlugins(): discovered plugin "AuthKeys" at "C:/Program Files/Veyon/plugins/authkeys.dll"
2021-10-18T13:47:29.786: [DEBUG] PluginManager::loadPlugins(): discovered plugin "BuiltinUltraVncServer" at "C:/Program Files/Veyon/plugins/builtin-ultravnc-server.dll"
2021-10-18T13:47:29.786: [DEBUG] PluginManager::loadPlugins(): discovered plugin "BuiltinDirectory" at "C:/Program Files/Veyon/plugins/builtindirectory.dll"
2021-10-18T13:47:29.802: [DEBUG] PluginManager::loadPlugins(): discovered plugin "Demonstration" at "C:/Program Files/Veyon/plugins/demo.dll"
2021-10-18T13:47:29.802: [DEBUG] PluginManager::loadPlugins(): discovered plugin "DesktopServices" at "C:/Program Files/Veyon/plugins/desktopservices.dll"
2021-10-18T13:47:29.802: [DEBUG] PluginManager::loadPlugins(): discovered plugin "ExternalVncServer" at "C:/Program Files/Veyon/plugins/external-vnc-server.dll"
2021-10-18T13:47:29.802: [DEBUG] PluginManager::loadPlugins(): discovered plugin "FileTransfer" at "C:/Program Files/Veyon/plugins/filetransfer.dll"
2021-10-18T13:47:29.802: [DEBUG] PluginManager::loadPlugins(): discovered plugin "LDAP Basic" at "C:/Program Files/Veyon/plugins/ldap.dll"
2021-10-18T13:47:29.802: [DEBUG] PluginManager::loadPlugins(): discovered plugin "PowerControl" at "C:/Program Files/Veyon/plugins/powercontrol.dll"
2021-10-18T13:47:29.817: [DEBUG] PluginManager::loadPlugins(): discovered plugin "RemoteAccess" at "C:/Program Files/Veyon/plugins/remoteaccess.dll"
2021-10-18T13:47:29.817: [DEBUG] PluginManager::loadPlugins(): discovered plugin "ScreenLock" at "C:/Program Files/Veyon/plugins/screenlock.dll"
2021-10-18T13:47:29.817: [DEBUG] PluginManager::loadPlugins(): discovered plugin "Screenshot" at "C:/Program Files/Veyon/plugins/screenshot.dll"
2021-10-18T13:47:29.817: [DEBUG] PluginManager::loadPlugins(): discovered plugin "SystemUserGroups" at "C:/Program Files/Veyon/plugins/systemusergroups.dll"
2021-10-18T13:47:29.817: [DEBUG] PluginManager::loadPlugins(): discovered plugin "TextMessage" at "C:/Program Files/Veyon/plugins/textmessage.dll"
2021-10-18T13:47:29.833: [DEBUG] PluginManager::loadPlugins(): discovered plugin "UserSessionControl" at "C:/Program Files/Veyon/plugins/usersessioncontrol.dll"
2021-10-18T13:47:29.833: [DEBUG] PluginManager::loadPlugins(): discovered plugin "WebAPI" at "C:/Program Files/Veyon/plugins/webapi.dll"
2021-10-18T13:47:29.848: [DEBUG] VeyonCore::initSystemInfo(): "4.6.0" "PC-00566-MDV.mdv.lan" "winnt" "10.0.19041" "Windows 10 (10.0)" "windows" "10"
2021-10-18T13:47:29.848: [DEBUG] FeatureWorkerManagerConnection::tryConnection(): connecting to FeatureWorkerManager at port 11300
2021-10-18T13:47:29.848: [INFO] VeyonWorker::VeyonWorker(): Running worker for feature "WindowDemo"
2021-10-18T13:47:29.848: [DEBUG] VeyonCore::exec(): Running
2021-10-18T13:47:29.848: [DEBUG] FeatureWorkerManagerConnection::sendInitMessage(): QUuid("{ae45c3db-dc2e-4204-ae8b-374cdab8c62c}")
2021-10-18T13:47:29.848: [DEBUG] FeatureManager::handleFeatureMessage(): feature "WindowDemo" command 2 arguments QMap(("0", QVariant(QByteArray, "\x9E\xE9\xD1\xFFIc&X\xF4\x9D-\x1B\xBF\xF8l:hY\xE5\x98\r\xADS\xED\x88""8P\t\x88I#H1l\xCD""8O\xD8\x8D""9\x82\xD3Y\xE2\xFBiZ=V\xEC(b\xE3\xA6\xBA""0\x81\x04""C \xECN\xBA\x17Wk\x84i\x92h\xA7\xE7G\xEA\x95P<\x18""b\xE6\xAFh1Z'\xE0\xC2\\?J&\x1A\xFF~&65\xAA\x10\x1B\x12\xA0\nl\n\x05P/\x13\xDDKb\xBC(\xCCP\x1E\xC7r\xB3""D*\xE7|\x92\xA6\xB1\x11"))("3", QVariant(QString, "::ffff:172.20.130.60"))("4", QVariant(int, 11400))("5", QVariant(QRect, QRect(0,0 0x0))))
2021-10-18T13:47:29.848: [DEBUG] DemoFeaturePlugin::handleFeatureMessage(): connecting with master "::ffff:@IP_MASTER"
2021-10-18T13:47:31.911: [DEBUG] VncConnection::rfbClientLogDebug(): 0x1d18 ConnectClientToTcpAddr6: connect
2021-10-18T13:47:31.911: [DEBUG] VncConnection::rfbClientLogDebug(): 0x1d18 Unable to connect to VNC server

Any idea ?

Thanks for your time.

[tatanas]

no support ?
Tested with Veyon 4.7 : same problem...

[tobydox]

@tatanas Any chance you can test with the internal VNC server and disable the external UltraVNC server instance temporarily? That would allow us to figure out whether your issues are related to the external VNC server feature in Veyon.