Mac-to-Mac Mode — USB Support

As of Luna Display version 5.3, we now support connecting in Mac-to-Mac mode with a USB cable – our recommended way of connecting. 

Table of Contents

USB Mac-to-Mac requirements
Compatible USB cables
How do I use Mac-to-Mac USB support?
USB Connection Troubleshooting

USB Mac-to-Mac requirements

USB Mac-to-Mac is only available in Luna Display 5.3  or later. USB Mac-to-Mac support requires:

  • Mac: macOS 10.15 or later on both Secondary and Primary computers
  • A compatible USB cable (see below)

Compatible USB cables

You will need either a USB-C to USB-C cable or USB-C to USB-A cable depending on how old the Mac is you'd like to use as your Secondary display.

Please note:
  • The USB-C cables from Apple that come with your iPad and Mac ARE NOT compatible with Mac-to-Mac mode – they are USB v2 cables while we require USB v3.1 or later.
  • USB hubs and adapters are also not compatible with Mac-to-Mac mode.

USB-C to USB-C Cables

If both your Primary and Secondary Macs support USB-C then you'll want to use a USB-C to USB-C cable. For Mac-to-Mac mode, we require USB-C cables that support at least USB v3.1 or later, but we recommend USB v3.2. When shopping for a cable look for one that lists support for v3.2 and mentions 20Gbps transfer with support for 4K @ 60hz video. 

Cables from Amazon we've tested and liked:
Note: Even though we have tested these cables, we cannot guarantee that these specific cables will work well with each setup. Use of these cables is at your discretion.

UseBean USB-C to USB-C v3.2 - 6.6ft

USB-C 3.2 Gen2x2 Cable v3.2 - 6.6ft

USB-C to USB-A Cables

If your Primary Mac supports USB-C but your Secondary Mac is older and only supports USB-A, then you'll want a USB-C to USB-A cable. In our testing, most USB-C to USB-A cables we tested worked. However to be certain that it will work for you, here are some cables we've tested:

Cables from Amazon we've tested and liked:
Note: Even though we have tested these cables, we cannot guarantee that these specific cables will work well with each setup. Use of these cables is at your discretion.

Amazon Basics USB-C to USB-A 2.0 Fast Charging Cable - 6 ft

Truntau USB-C to USB-A 2.0 Cable - 3.3

USB-A to USB-A Cables

Unfortunately, USB-A to USB-A cables are not supported at this time for Mac-to-Mac mode.

How do I use Mac-to-Mac USB support?

  1. Connect your Primary and Secondary Mac together using the appropriate USB cable
  2. Launch the Luna Display app on the Primary Mac and Luna Secondary app on the Secondary mac
  3. Plug your Luna into your Primary Mac
  4. You should be all set!

How can I tell if it's connected over USB?

On your Primary Mac, while it's connected, bring the Luna Display app to the front. In the upper right corner of the Luna Display Settings window, you'll see a connection indicator in the upper right corner. When it's connected over USB there will be a cable present.

USB Connection Troubleshooting

Are you having trouble getting a USB Mac-to-Mac connection? Here are some troubleshooting tips for common problems:

USB doesn't connect 

Here are a few things to check:

  • Make sure your USB cable and MacOS versions meet the requirements listed above
  • Do not plug the USB cable into any hubs or adapters - try plugging the USB cable directly into the computer's port

Once you've checked the above requirements, try this:

  1. Quit the Primary and Secondary Luna apps on both computers
  2. Plug in the USB cable
  3. Relaunch the Primary and Secondary Luna apps
  4. A USB connection should establish
  5. If not, try restarting both computers and run through the above again.
  6. If it still doesn't work, it's likely your cable or MacOS version isn't compatible.

Note: It helps to have the USB cable plugged in BEFORE you launch the Luna Primary and Secondary apps as it's more likely to detect the cable. 

A "Cannot Use Thunderbolt Accessory" system alert appears

This is likely due to an incompatible cable. Please visit our article that goes in-depth on this topic. 

USB disconnects after waking from sleep

If after waking your computer from sleep Luna connects over Wifi instead of USB, then you'll need to quit the Secondary app and then relaunch it to connect again over USB. This is a known bug that we expect to fix in our next minor update.

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