For the best performance using Duet, connect your Duet-enabled Mac and Windows devices via Thunderbolt cables. Duet Over Thunderbolt is a powerful feature that provides multiple benefits versus standard network connections:

• Thunderbolt allows incredible transmission speeds - at least 10Gb/s.
• Thunderbolt has virtually no lag - less than 1ms for Mac-to-Mac connections.
• Thunderbolt keeps your video stream off of your network. This is especially valuable for 4k+ streams due to the high bandwidth needed.

Hardware Requirements

This feature requires Thunderbolt 3 or higher. You'll also need a Thunderbolt cable and two computers with compatible Thunderbolt ports. Make sure that the cable you have is compatible with both ports. Depending on your device’s age, it may support only the original Thunderbolt, Thunderbolt 2, 3, 4, or even 5. Check your device's technical specifications to find out which Thunderbolt cable type it supports.

Thunderbolt 3+ cables are typically USB-C, but not all USB-C ports on your device necessarily support Thunderbolt; look for a lightning icon next to the port.

There are different configuration instructions for Mac-to-Mac, Windows-to-Windows, and Mac-to-Windows. These steps are only needed for the first connection. After that, simply connect the Thunderbolt cable and Duet will use it automatically.

Note: For Windows devices, you must have a minimum of Windows 10 version 1709 or later.

Configuring Mac-to-Mac

1. Close Duet on both systems.
2. Plug one end of the cable into each Mac, making sure you choose a Thunderbolt-capable port. You can plug the cable in while the Mac is running; the cable should be detected and activated by macOS automatically.
3. Once the two Macs are connected by the Thunderbolt cable, open the macOS System Preferences and choose Network on the sidebar.
4. The "Thunderbolt Bridge" is the connection over the Thunderbolt cable. If you do not see this, macOS has not detected your Thunderbolt connection, and you may need to change the cable or the port in which it is inserted.
5. By default, the Thunderbolt Bridge will come up unconfigured, with a red dot. After a short delay (once both Macs are connected), macOS will assign it a "Self-Assigned IP", and display a yellow dot. The Thunderbolt cable is usable at this point, and Duet will use it automatically.
6. Open Duet on both systems and start connecting - you're ready to go! You can confirm the connection is using thunderbolt by seeing a ⚡icon appear in the lower left corner of the main duet application window (not the stream window).
7. Note: If Duet does not report that your connection(s) are using thunderbolt it is recommended to instead set a static IP address for the Thunderbolt Bridge. If you do this it must be done on both Macs, and they must have different IP addresses that are in the same subnet. To do so, follow of the Mac-to-Windows guide below. Once both Macs have IP addresses with corresponding subnet masks, the dot next to the Thunderbolt Bridge in the macOS networking settings should appear green. After this is done restart duet on each Mac (should only be needed once) and retry the connection.

Configuring Mac-to-Windows

• Enable internet sharing on the Mac. Note: This step is only needed when connecting to a Windows 10 device. If you have Windows 11 on your other device, you may skip to step 2.

             a. Open System Settings, click General in the sidebar, then click Sharing on the right.

             b. Click the Info button next to Internet Sharing.

             c. Click the “Share your connection from” pop-up menu, then choose the internet connection you want to share. For example, if you’re connected to the internet                  over Ethernet, choose Ethernet.

             d. In the “To computers using” list, select Thunderbolt Bridge.

             e. Click done, then turn on the toggle for internet sharing.

• Set the Thunderbolt Bridge on Mac to Manual IP.

             a. Open System Settings, click Network in the sidebar, then click Thunderbolt Bridge on the right.

             b. Open the “Details…” menu, then click TCP/IP on the left.

             c. Toggle “Configure IPv4” to “Manually”.

             d. You will need to fill in both the "IP Address" and "Subnet Mask" fields. The address should not be in the same subnet as any of the other networks listed in the                  Network panel of System Preferences. A good choice for most networks is 10.10.10.1 and 255.255.255.0.

             e. Hit Ok to confirm.

• Plug in the Thunderbolt cable and wait for the connection to fully initialize.

• Set a manual IP address for the Windows Thunderbolt Bridge adapter. Use the same subnet mask as the Mac device and another IP address within that range. For example, 10.10.10.2 and 255.255.255.0 would match with the above recommendation. Note: Each Thunderbolt port on your PC is treated as a separate network adapter by Windows, so you’ll need to repeat this step for each port you plan to use in the future.

              a. Open the Network and Sharing center, then click “Change adapter properties”.

              b. Right click on the thunderbolt bridge and click Properties.

              c. Make sure the box is checked for “Internet Protocol Version 4 TCP/IPv4”.

              d. Change the properties of TCP/IPv4 to use another IP on the subnet such as 10.10.10.2 and set the subnet to 255.255.255.0.

• Unplug the Thunderbolt cable, and restart the Windows machine.
• Once you are logged back in to Windows, plug in the Thunderbolt cable and wait for the connection to fully initialize.
• At this stage, Duet over Thunderbolt should be ready to go! Once you start a connection from either side, you can confirm Duet is connecting over thunderbolt by checking that a lightning icon (⚡) is present in the bottom left corner of the Mac UI or by checking that a lightning icon (⚡) exists on the Windows UI next to the connection name. If not, you may need to restart Duet on both devices to register the new IPs.

Configuring Windows-to-Windows

Note: This feature works by sharing your internet connection from one of your PCs to the other. We will refer to the PC sharing internet as PC1, and the device receiving the internet share as PC2.

1. On Both PCs: Enable private network sharing on Windows.
   • Go to Start > Settings > Network & Internet > Status > Change advanced sharing options.
   • Under the "Private" section, turn on "Network discovery" and "File and printer sharing".
2. Plug one end of the cable into each PC, making sure you choose a Thunderbolt-capable port.
3. On Both PCs: Open Control Panel > Network and Internet > Network Connections. You should now see a new network labeled similar to: "Ethernet X / Unidentified network / Thunderbolt Networking”. If not, you may need to set the new Thunderbolt network to “private”. There are two ways to do this:
   • On Win 10 or 11: Open File Explorer. Scroll down on the left Quick Access Bar until you see the new network, then open it. There should now be a prompt below the address bar, click it. Choose to enable sharing and make this network private.
   • On Win 11: Open Settings > Network & internet > Advanced Network Settings. Then select the connected network and choose "Private" under "Network profile type" to make your computer discoverable on the network.
   • After following either of the above, you should now see the new Ethernet Thunderbolt adapter in “Network Connections”.
4. On PC1: Enable internet sharing across Thunderbolt.
   • Go to your Windows settings and navigate to "Network & Internet" > "Status" > "Change adapter settings".
   • Right-click on the network adapter you want to share (your active internet connection) and select "Properties".
   • Go to the "Sharing" tab and check the box next to "Allow other network users to connect through this computer's Internet Connection".
   • Under "Home network connection", choose the name of the thunderbolt network from the dropdown menu. Hit ok to close.
5. On PC2: Configure the Thunderbolt Adapter IP address.
   • Disable WiFi or unplug Ethernet. This will allow you to confirm that the internet share is working correctly.
   • Go to your Windows settings and navigate to "Network & Internet" > "Status" > "Change adapter settings".
   • Right-click on the Thunderbolt network adapter and select "Properties".
   • Select Internet Protocol Version 4 from the list and click "Properties"
   • Set IP/DNS to "obtain automatically". If the test below doesn't work, you may need to set a static IP that matches the other PC's IP/DNS.
   • Test a website to confirm you now have internet again.
   • [Optional] If desired you may re-enable your typical WiFi/Ethernet connection now. However, leaving it off guarantees that the Thunderbolt connection is used instead of your main network.
6. On Both PCs: Open Duet and start connecting - you're ready to go!

Testing

To check if the Thunderbolt Bridge is working outside of Duet, open a command line terminal (such as Terminal.app or cmd). Then use the 'ping' command with the Thunderbolt Bridge IP address of the other computer. For example, ping -c 5 10.10.10.1.

‍Note: If you are testing with Windows, you will need to allow ping through your Windows firewall.

• If you see 0% packet loss as shown above, your connection is working correctly.
• If you see Request timeout for icmp_seq or more than 0% packet loss, double-check the IP address to ensure it was entered correctly. If the IP matches the one you assigned to the other device’s Thunderbolt Bridge then there is an issue with your connection.
• If ping is not working in either direction there may be an issue with your Thunderbolt cable, or it may not be plugged in correctly.

You can check this article on how to troubleshoot your TB connection when Thunderbolt Bridge is not connected.

If you have any questions or require assistance, please reach out to us at team@duetdisplay.com - we're happy to help!