spacedesk lets one device display an extended or mirrored desktop from another supported computer. Install the driver/server on the main computer and the viewer on the device used as the extra screen. Connecting two devices to the same Wi-Fi alone does not create a second monitor.
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Which device needs which software?
| Role | What runs there | What to check |
|---|---|---|
| Main computer | spacedesk driver/server. | Supported operating system and driver version. |
| Extra screen | spacedesk viewer, or a supported browser-viewer route. | The viewer for that device and connection type. |
| Connection | Supported local network or USB setup. | Follow the platform-specific connection instructions. |
The current system requirements list Windows 10/11 main computers and a macOS 14.4-or-later driver marked beta. Viewer support is a separate list. Do not confuse “a Mac can be a viewer” with “every Mac can run every server version.”
Set it up for a Windows computer
- Get the matching Windows driver from the official spacedesk website and check its current terms.
- Install it on the main computer and restart if requested.
- Install the supported viewer on your phone, tablet or second computer.
- For a local-network connection, put both devices on a network where they can reach each other.
- Open the viewer and connect to the main computer shown.
The official setup manual explains the server/viewer arrangement. A guest Wi-Fi network can isolate devices even when they appear to share the same router.
Extend the desktop rather than duplicate it
Once connected, open Windows display settings. Choose Extend if you want different windows on each screen, or Duplicate if you want the same picture. Arrange the display rectangles to match the devices’ physical positions so the pointer crosses the expected edge.
If you need the same program visible in two windows, our multiple-window guide explains the app-side step. Adding a monitor does not create another independent copy of the app.
Fix a missing computer or slow connection
- Confirm the main computer’s server is running and you installed the correct roles.
- Check guest-network isolation, VPN routing and the manual’s connection instructions.
- Allow the supported app through the firewall for the trusted network instead of switching the firewall off entirely.
- Try a lower resolution or a supported wired/USB route if wireless performance is poor.
- Compare performance before changing several settings at once.
For a weak wireless link, see our router-placement guide. Use the connection modes actually supported by the two devices, not a random USB cable assumption.
Is an old phone suitable?
It can be useful for a chat window, reference material or simple controls. Latency, screen size, battery condition and app support can make it less suitable for fast gaming or color-critical work. Our old-phone checklist helps decide whether keeping the device is worthwhile. Check current licensing and platform notes instead of relying on old promises about a future “Pro” edition.