UltraVNC Extend Display - Frequently Asked Questions

Where are the logs?

Server/service logs are written to:

C:\ProgramData\UVNCExtDisp\service.log
C:\ProgramData\UVNCExtDisp\helper.log

If the service cannot write there, it falls back to:

 C:\ProgramData\UVNCExtDisp\service.log

The client says "No UltraVNC Extend Display server found on the LAN"

• • Make sure the desktop PC has the service installed and running:

cmd
sc.exe query UVNCExtDisp

• • If it is STOPPED, start it from an elevated prompt:

sc.exe start UVNCExtDisp

• • Make sure both PCs are on the same network and the firewall allows TCP 5950 and UDP 5951.

• • If the desktop PC was locked, unlock it. The service does not stream a locked session for security reasons; the client reconnects automatically once unlocked.

Does the client connect automatically?

Yes. When you run ultravnc_extdisp.exe without a host name, it auto-discovers a server on the LAN and connects immediately. If you click Discover in the connect dialog, it also connects automatically as soon as a server is found.

Why does the extra monitor freeze when the desktop PC is locked?

Windows blanks the DXGI Desktop Duplication feed while the session is locked. This is an OS-level limitation, not a bug in UltraVNC Extend Display. The client automatically resumes when the session is unlocked.

Can I use this over the Internet or through NAT?

No. v1 is LAN only. Future versions may add repeater or relay support.

Does the client send keyboard/mouse/touch input back to the desktop?

No. The client is display-only. It is intended to be an extra monitor, not a remote-control session.

Do I need to run the client as Administrator?

No. Only the server/service needs elevation (for the virtual-display driver and the Windows service).

Is the driver signed?

Yes. The package included in the installer is signed by uvnc bvba.

I uninstalled but the service is still listed?

Run an elevated Command Prompt and remove it manually:

sc.exe stop UVNCExtDisp
sc.exe delete UVNCExtDisp