How to Share PC Screen via Ethernet Cable Without a Router or Internet

While Wi-Fi is convenient, high-resolution screen sharing over wireless signals can suffer from microwave interference, thick walls, and fluctuating bandwidth. Furthermore, in industrial control rooms, server closets, ships, or air-gapped test labs, wireless transmitters might be forbidden altogether.

Connecting two computers directly with a standard Ethernet cable (RJ45) provides a rock-solid, ultra-low latency connection with up to 1 Gbps or 2.5 Gbps of dedicated bandwidth. With ScreenTask, you can stream your primary PC’s display to a second laptop or desktop over an Ethernet cable with no router, no switch, and zero internet connection.

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Why Use Direct Ethernet for Screen Sharing?

1. Immunity to Radio Congestion: Unlike 2.4 GHz and 5 GHz Wi-Fi channels that compete with smartphones, Bluetooth devices, and microwaves, copper Ethernet cables deliver steady, jitter-free throughput.
2. Sub-Millisecond Network Latency: Direct cable connection reduces network packet transit time to under 1 millisecond.
3. No Expensive Crossover Cable Required: All modern network interface cards (NICs) support Auto-MDIX, which automatically detects cable orientation and configures the internal TX/RX pins. Any standard Cat5e, Cat6, or Cat6a patch cable will work.
4. Physical Air-Gap Security: Your video data physically cannot be intercepted outside the copper cable link.

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Step 1: Connect the Two Computers

1. Take a standard Cat5e or Cat6 Ethernet cable.
2. Plug one connector into the host computer’s Ethernet port (the PC whose screen you want to share).
3. Plug the other connector into the client computer’s Ethernet port (the laptop or secondary PC where you want to view).
4. Verify that the Ethernet link lights on both network ports flash green or amber, indicating physical layer negotiation.

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Step 2: Configure IP Addresses (Static IP vs. APIPA)

When two computers are connected directly without a router or DHCP server, you have two options for IP assignment:

Option A: Automatic APIPA (Easiest - Zero Configuration)

Modern versions of Windows automatically assign an APIPA (Automatic Private IP Addressing) address within the 169.254.x.x range when no DHCP server is detected:

1. Wait 30 seconds after plugging in the cable.
2. Open Command Prompt (cmd) on the host PC and run ipconfig.
3. Locate the Ethernet adapter section and note the Autoconfiguration IPv4 Address (e.g., 169.254.45.120).

Option B: Assign Static IP Addresses (Recommended for Speed & Stability)

For permanent or repeatable setups, manual static IPs prevent address renegotiation:

On Host PC (Broadcaster):

• IP Address: 192.168.2.1
• Subnet Mask: 255.255.255.0
• Default Gateway: (Leave blank)

On Client PC (Viewer):

• IP Address: 192.168.2.2
• Subnet Mask: 255.255.255.0
• Default Gateway: (Leave blank)

To set this on Windows:

1. Press Win + R, type ncpa.cpl, and press Enter (opens Network Connections).
2. Right-click your Ethernet adapter $\rightarrow$ Properties.
3. Double-click Internet Protocol Version 4 (TCP/IPv4).
4. Select Use the following IP address and enter the numbers above. Click OK.

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Step 3: Launch ScreenTask on the Host PC

1. Download and run ScreenTask on the host PC from the ScreenTask Download Hub.
2. In the IP dropdown, select the Ethernet interface address (e.g., 192.168.2.1 or the 169.254.x.x APIPA address).
3. Set Port to 7070 (or 9000).
4. Set Refresh Rate to 200 ms or 100 ms (because Ethernet easily handles high-frequency image updates).
5. Click Start Server.

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Step 4: Open the Stream in the Client Browser

1. On the client computer, open your web browser (Google Chrome, Microsoft Edge, Firefox).
2. Type the host PC’s Ethernet URL into the address bar:

   http://192.168.2.1:7070

   (Or your 169.254.x.x:7070 address if using Option A).
3. Press F11 to view the stream in fullscreen mode.

[!TIP] If the page does not load, open Windows Defender Firewall on the host PC and ensure an inbound exception is granted for port 7070 across Private profiles, or run New-NetFirewallRule -DisplayName "ScreenTask Ethernet" -Direction Inbound -LocalPort 7070 -Protocol TCP -Action Allow -Profile Any in PowerShell.

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Using an Unmanaged Ethernet Switch for Multi-Client LAN Sharing

If you want to broadcast one PC screen to 3, 5, or 10 laptops via Ethernet cables simultaneously:

1. Connect an inexpensive 5-port or 8-port Gigabit unmanaged switch.
2. Run an Ethernet cable from each computer into the switch.
3. Assign each machine a unique static IP on the same subnet (192.168.2.1 for host, 192.168.2.2, 192.168.2.3, etc. for viewers).
4. All client machines can now access http://192.168.2.1:7070 simultaneously with zero Wi-Fi drops.

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Related Guides & Resources

• How to Share Your Screen Offline Over LAN & Wi-Fi
• How to Share PC Screen Over Wi-Fi Without Internet
• Troubleshooting Connection Refused and Port Errors
• Download ScreenTask Standalone Executable