How to Share Your Screen Offline Over a Local Network (LAN & Wi-Fi)

Sharing a computer screen usually relies on cloud-based remote desktop software like TeamViewer, Zoom, or Google Meet. However, when you are working in an offline environment, an air-gapped network, a classroom, or simply dealing with a slow or non-existent internet connection, cloud tools fail completely.

ScreenTask solves this problem by turning your computer into a lightweight, local HTTP streaming server. Any device on the same local network—whether connected via Wi-Fi or an Ethernet cable—can view your screen in real time using nothing more than a standard web browser.

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Why Share Your Screen Offline?

There are several compelling reasons to use local network screen mirroring instead of cloud services:

1. Zero Bandwidth Consumption: High-resolution screen mirroring never leaves your local area network (LAN). Your monthly internet data quota remains untouched.
2. True Air-Gapped Privacy: Because video frames are transmitted directly between devices on your router or switch, sensitive presentations, financial documents, and code never touch external servers or third-party cloud infrastructure.
3. No Software Required for Viewers: Viewers do not need to create accounts, download companion apps, or install browser extensions. They simply open Chrome, Safari, Edge, or Firefox and enter your local IP address.
4. Reliability in Remote Areas: Ideal for field work, construction sites, ships, offline training centers, and conference rooms where internet connectivity is absent or unstable.

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Prerequisites

Before starting, ensure you have:

• A host computer running Windows 11, 10, 8, 7, or Vista (or Linux/macOS with the Java runtime).
• ScreenTask v1.2 installed or downloaded as a portable executable.
• Both the host computer and viewer devices connected to the same local network (Wi-Fi router, Ethernet switch, or mobile hotspot).

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Step 1: Find Your Local IP Address

To let other devices connect, you need your host PC’s private local IPv4 address (usually starts with 192.168.x.x or 10.x.x.x).

ScreenTask automatically detects and lists all available network adapters in its drop-down menu. However, you can also verify your IP manually via the command line:

1. Press Win + R, type cmd, and press Enter.
2. Run the following command:

   ipconfig

3. Locate your active network adapter (Wireless LAN adapter Wi-Fi or Ethernet adapter) and note the IPv4 Address (for example: 192.168.1.105).

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Step 2: Configure ScreenTask

Launch ScreenTask on your computer. You will see the main configuration control panel:

1. Select Network IP: From the IP drop-down menu, choose the IPv4 address corresponding to your active local connection (e.g., 192.168.1.105). Avoid selecting 127.0.0.1 (localhost), as that only allows connections from the same PC.
2. Port Number: By default, ScreenTask uses port 9000 (or 7070). You can keep the default unless another application on your system is already using that port.
3. Select Display: If you have a multi-monitor workstation, select which monitor you want to broadcast from the Display drop-down.
4. Refresh Interval & Quality:
   • Refresh Rate: Set how frequently a frame is captured (e.g., 500 ms for balance, or 200 ms for faster motion).
   • Image Quality: Balance visual clarity against local network throughput. A quality setting between 70% and 85% is ideal for crisp text without congesting Wi-Fi bandwidth.

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Step 3: Optional Security & Password Protection

If you are sharing your screen in a public space, school lab, or shared co-working office, you can restrict access:

1. Check the Private Task / Password option.
2. Enter an authorized Username and Password.
3. When viewers navigate to your address, their browser will prompt them with HTTP Basic Authentication before revealing the screen stream.

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Step 4: Start Broadcasting

Click the Start Server button. ScreenTask will automatically:

• Bind the internal HTTP listener to your selected IP address and port.
• Open the required Windows Firewall rule for the session.
• Begin capturing periodic screenshots of the chosen display.

The status indicator in ScreenTask will switch to Running, displaying the exact URL viewers should open (e.g., http://192.168.1.105:9000).

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Step 5: Connect Viewers via Web Browser

On any client device—including iPhone, iPad, Android smartphones, laptops, Chromebooks, or Smart TVs:

1. Connect the client device to the same Wi-Fi network or Ethernet switch.
2. Open any modern web browser (Google Chrome, Apple Safari, Mozilla Firefox, or Microsoft Edge).
3. Type the full URL shown in ScreenTask into the address bar:

   http://192.168.1.105:9000

4. If password protection is enabled, enter your credentials.

The screen stream will immediately appear in the browser window, updating live as you work on your computer. Viewers can rotate their phones to landscape or press F11 on desktop browsers for a full-screen view.

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Troubleshooting Common Network Issues

Viewers Cannot Reach the URL (“This site can’t be reached”)

• Network Profile: Ensure your Windows network profile is set to Private, not Public. Windows blocks incoming traffic by default on Public networks.
• Firewall Restrictions: Make sure Windows Defender Firewall allows incoming TCP traffic on your chosen port. See our dedicated Windows 11 Firewall & Port Configuration Guide.
• AP / Client Isolation: Some guest Wi-Fi routers enable “Client Isolation” (which prevents devices on the same Wi-Fi from communicating with each other). If this is enabled on your router, connect via a personal router, mobile hotspot, or an Ethernet switch.

Stream Appears Choppy or Laggy

• Lower the screenshot refresh interval or reduce image quality to 60–70% in ScreenTask settings.
• Ensure the host computer is not running at 100% CPU utilization.
• For optimal performance with multiple concurrent viewers, connect the host computer via an Ethernet cable rather than Wi-Fi.