UltraVNC Extend Display - Installation Guide

 

System requirements

    • Windows 10 or Windows 11
    • A wired or Wi-Fi LAN connection between the desktop PC and the laptop/spare PC
    • Administrator rights for the installer (UAC prompt)
    • Server component requires 64-bit Windows 10 version 1903 (build 18362) or later
    • Client (monitor) component works on both 32-bit and 64-bit Windows

What the installer contains

UltraVNC_Extend_Display_Setup.exe contains both 32-bit and 64-bit versions of the client and installs the correct one for the OS. You can choose which components to install:

    • Server — ultravnc_extdisp_service.exe, ultravnc_extdisp_server.exe, and the signed UVncVirtualDisplay driver package
    • Client — ultravnc_extdisp.exe (the extra-monitor viewer)

The installer also opens the Windows Firewall for the required ports and registers the UVNCExtDisp service.

Quick install

    1. Download UltraVNC_Extend_Display_Setup.exe.
    2. Right-click it and choose Run as administrator.
    3. Accept the UAC prompt.
    4. On the components page, choose:

- Server on the desktop PC that will be extended (only offered if supported).

- Client on the laptop or spare PC that will act as the extra monitor.

    1. If Server is selected, the installer will:

- Copy the files to C:\Program Files\UltraVNC Extend Display\

- Install the signed virtual-display driver

- Register and start the UVNCExtDisp Windows service

- Add Windows Firewall rules for TCP 5950 and UDP 5951

    1. When the installer finishes, the server is already running.

Connect a laptop as an extra monitor

On the laptop/spare PC, run the installed ultravnc_extdisp.exe:

ultravnc_extdisp.exe

The client automatically discovers a server on the LAN and connects. You can also start it with a specific host:

ultravnc_extdisp.exe <desktop-pc-name-or-ip> [port]

Press Escape to exit the client.

Manual/test mode (no service)

For testing or development, you can run the server interactively without the service:

From an elevated Command Prompt on the desktop PC:


cd /d "C:\Program Files\UltraVNC Extend Display"
ultravnc_extdisp_testapp.exe [-port 5950]

This still needs elevation because it does not run as LocalSystem. The client connects the same way.

Network ports

    • TCP 5950 — the actual screen stream
    • UDP 5951 — discovery beacons

The installer attempts to add firewall rules for these automatically. If you run the firewall manually, allow inbound TCP 5950 and UDP 5951.

Uninstall

Use Apps > Installed apps in Windows Settings and uninstall UltraVNC Extend Display. The uninstaller stops and removes the service, removes the firewall rules, and deletes the files.

If the service is still listed after uninstall, remove it manually from an elevated Command Prompt:

sc.exe stop UVNCExtDisp

sc.exe delete UVNCExtDisp