Computer-to-Mac — How to Connect Your Computers

What is Computer-to-Mac Mode?

Luna Display’s Computer-to-Mac mode lets you use a Mac as a second display for your primary Mac or PC.

Please note:

iMacs can be used as Retina displays with some limitations. More details here.
M1–M4 Macs are supported, but may have limits on external displays. Check your model's tech specs and see more info here.
If you're using a Mac Mini M4 or Mac Studio, plug Luna into a rear port — front ports do not support display connections.

Connecting over Wi-Fi

Connect both Macs to the same Wi-Fi network.

They must be on the same network to find each other. You can also use an Ethernet or Thunderbolt cable instead.
Open the Luna Primary app on your main computer.

This is the Mac or PC where the Luna hardware is plugged in. The icon is a grey and white cat.
Make sure permissions are enabled:
- For macOS Mojave: Enable Accessibility
- For macOS Catalina or later: Enable Screen Recording
Luna never saves or records your screen.
Open the Luna Secondary app on the Mac you want to use as a second display.

The icon is a black and grey cat.
Both computers should automatically connect!

Using USB, Ethernet, or Thunderbolt

You can also connect your computers directly with a Ethernet, Thunderbolt, or USBcable. Luna hardware must still be plugged into your primary Mac or PC.

USB connections are only compatible with Mac-to-Mac modes running macOS 10.15 or later.

Ethernet is recommended for PC-to-Mac mode, as Thunderbolt has proven to be more unreliable with PC setups.

How to use a USB, Ethernet, or Thunderbolt connection

Manual Connect

When should I use Manual Connect?

Manual Connect is most commonly used in two situations:

Wi-Fi connections: When devices are on the same network but still aren’t connecting automatically or you have Public Mode turned on, Manual Connect allows you to enter a code to link them directly.
Wired connections: When using USB, Ethernet, or Thunderbolt and the connection doesn't establish on its own, Manual Connect is a helpful fallback to force the connection manually using your cable's IP address.

If your devices are having trouble discovering each other, Manual Connect is a quick and reliable way to get them linked.

Choose “Manual Connect” in both Luna apps.
Look for the four-part code in the Luna Primary app.
The code on the Secondary Mac will have missing digits.
Complete the code by entering the missing digits into the Secondary Mac. You can also delete the pre-populated numbers and enter the IP of your choosing manually.
Tap “Connect” on the Secondary Mac. You’re all set!

If your computers don't connect automatically:

Make sure both are on the same Wi-Fi network
Confirm both are on the same Wi-Fi band (2.4GHz or 5GHz)
Check that both apps are open and running
Try Manual Connect
Try a wired connection (USB, Ethernet, or Thunderbolt): How to connect with a cable