Dual & Multi-Monitor Screen Sharing: How to Select and Stream Specific Displays

When presenting slides, demonstrating software, or teaching over a local network, multi-monitor setups are standard. A common workstation configuration includes an internal laptop display alongside an external 24-inch or 27-inch HDMI/DisplayPort monitor.

The biggest hazard during live presentations is accidental data leakage: sharing your primary monitor where private emails, Slack direct messages, sensitive passwords, or presenter notes are open.

ScreenTask includes native multi-monitor support, allowing you to select and stream a specific display (e.g. Display 2) across your local network while keeping your primary workstation screen private.

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Why Isolate Your Shared Monitor?

1. Presenter Privacy: Keep slide speaker notes, upcoming topics, and timer clocks visible on Screen 1 without your audience seeing them.
2. Prevent Confidential Spills: Unsolicited chat notifications, incoming email alerts, and confidential company dashboards stay safely confined to your unshared display.
3. Optimized Aspect Ratio: Choose a 16:9 monitor (1080p) for clean mobile and projector viewing, even if your primary laptop display has an unusual 16:10 or 3:2 aspect ratio.

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Step 1: Identify Your Displays in Windows

Before configuring ScreenTask, verify which display number Windows assigns to each physical monitor:

1. Right-click any empty area on your desktop and select Display settings.
2. Click the Identify button. Windows will display a large numeral “1” or “2” in the corner of each physical monitor.
3. Note which monitor contains your presentation content (typically Display 2).

[ Physical Workstation Layout ]
+----------------------+      +----------------------+
|     Display 1        |      |     Display 2        |
|  (Private Notes,     |      |  (Public Slides,     |
|   Chat, Email)       |      |   Demo, Code)        |
+----------------------+      +----------------------+
     [ KEEP PRIVATE ]             [ STREAM OVER LAN ]

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Step 2: Configure Display Selection in ScreenTask

1. Download and open ScreenTask from the ScreenTask Download Hub.
2. Look for the Select Screen (or Display) dropdown menu.
3. ScreenTask automatically queries the Windows Graphics Device Interface (System.Windows.Forms.Screen.AllScreens) and enumerates all active monitors:
   • Display 1 (Primary: 1920x1080)
   • Display 2 (Secondary: 1920x1080)
4. Select the specific monitor you intend to broadcast (e.g., Display 2).
5. Select your network IP and port (e.g., 192.168.1.15:7070).
6. Click Start Server.

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Step 3: Verify the Stream on a Secondary Device

Before beginning your presentation or meeting:

1. Open a browser tab on your smartphone or a second device on the same Wi-Fi network.
2. Navigate to http://<YOUR-IP>:7070.
3. Confirm that the stream strictly captures the contents of Display 2.
4. Move your mouse or drag a window across Display 1: notice that viewers on Display 2 see zero movement or interference.

[!TIP] Windows DPI Scaling Tip: If your secondary monitor uses high-DPI scaling (e.g. 4K at 150% or 200%), text rendering might appear slightly oversized in viewer browsers. In Windows Settings $\rightarrow$ Display, consider setting the secondary monitor scaling to 100% for crisp, native 1:1 pixel rendering.

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Dynamic Multi-Monitor Adjustments During Live Sessions

• Switching Displays on the Fly: If you need to switch from Display 2 back to Display 1 midway through a demo, click Stop Server in ScreenTask, change the display dropdown to Display 1, and click Start Server. Viewers’ browsers will automatically pick up the new display feed within a second without requiring a browser refresh.
• Minimizing ScreenTask: Check Minimize to System Tray in ScreenTask settings to keep the control panel off both displays entirely.

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Related Guides & Resources

• Classroom Screen Sharing Guide for Teachers & Labs
• How to Use a Tablet as a Wireless Second Screen
• Windows 11 Setup, SmartScreen & Firewall Guide
• Download ScreenTask v1.2