DirectConnect

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Two laptops connected with USB-C and nothing happens

Nothing appears because macOS, Windows and Linux don’t share files with another computer when you plug in a cable. If both laptops have Thunderbolt or USB4, the cable quietly creates a network link, and you turn on file sharing, set up an account and connect by address before any files show up.

Why this is harder than it should be

  • There’s no plug-and-play between computers. Plug in a phone or a drive and your computer knows what to do. Plug in another computer and it has no built-in “show me its files” behaviour.
  • Not every USB-C port or cable can do it. Both laptops need Thunderbolt or USB4, and the cable has to carry data. A plain USB-C port or a charging cable gives you no link at all.
  • The connection is invisible. The link shows up as Thunderbolt Bridge on a Mac, a new Ethernet adapter on Windows and thunderbolt0 on Linux. Nothing on screen tells you it’s there.
  • File sharing is off by default. Every system keeps it switched off to protect your files, so the other computer sees nothing until you turn it on and choose what to share.
  • Windows blocks it on new connections. Windows treats the cable as a Public network, where discovery and file sharing stay off.
  • You need an account and an address. The other computer signs in with a user name and password on the sharing computer, and you connect using a self-assigned 169.254 address.
  • It doesn’t stay connected. Unplug the cable, close the lid or restart, and you connect again, sometimes to a new address.

A direct link needs Thunderbolt 3 or newer, or USB4, on both laptops. Look for a lightning-bolt symbol or a “USB4”, “40Gbps” or “20Gbps” label next to the port. Plain USB-C ports can’t connect two computers. If you’re not sure, see how to tell if your laptop has Thunderbolt or USB4.

Check the cable too. The cable that came with a phone or charger is often USB 2.0 or charging-only, and doesn’t carry the link. If one laptop starts charging the other but no network link appears, suspect the cable or the port. See which USB-C cable you need.

With the cable plugged in, look for the new connection on each computer:

  • Mac: in System Settings, choose Network. Thunderbolt Bridge shows a green dot when the link is up. Choose Thunderbolt Bridge > Details… > TCP/IP to see its address.
  • Windows: in Settings, choose Network & internet > Advanced network settings. Under Network adapters, look for a new Ethernet connection, such as Ethernet 2, described as USB4(TM) P2P Network Adapter or Thunderbolt(TM) Networking.
  • Linux: in a terminal, run ip addr show thunderbolt0. If the command says the device doesn’t exist, the link isn’t up.

With no router on the cable, each computer gives itself an address starting with 169.254. That’s normal here. On Linux, if thunderbolt0 has no IPv4 address, open the wired connection’s settings and set IPv4 to Link-Local Only.

If the link is there, the cable works. What’s missing is file sharing. If no new connection appears on a Windows PC, that PC may not support PC-to-PC networking on this port: try another USB4 or Thunderbolt port.

3. Turn on file sharing on the computer with the files

On a Mac

  1. In System Settings, choose General > Sharing and turn on File Sharing.
  2. Click the info button next to File Sharing, add the folders to share, and choose who can open them.
  3. If a Windows PC will connect, click Options…, and under Windows File Sharing, select your account and enter its password.

On Windows

  1. In Settings, choose Network & internet, then the cable’s connection, such as Ethernet 2. It shows as Unidentified network.
  2. Under Network profile type, select Private network.
  3. Go back and choose Advanced network settings > Advanced sharing settings. Under Private networks, turn on Network discovery and File and printer sharing.
  4. In File Explorer, right-click the folder and choose Properties. On the Sharing tab, click Share….
  5. Choose the account that will sign in, click Add, set its Permission Level, and click Share.

If Windows asks whether to turn on network discovery for all public networks, the cable is still on a Public network. Set it to Private network as above instead.

On Linux

A Linux computer shares folders through Samba, which you install and set up with a Samba password. The steps depend on your distribution: see Mac and Linux.

4. Choose the account to sign in with

The other computer signs in with an account on the computer that has the files. Windows 11 doesn’t allow sharing without a password.

  • Sharing from a Mac: use your Mac user name and login password.
  • Sharing from Windows with a Microsoft account: the user name is the account’s email address, and the password is the Microsoft account password, not the Windows Hello PIN.
  • Sharing from Windows with a local account: use its name and password. If the same user name exists on both computers, type the sharing PC’s name first, such as DESKTOP-ABC123\sharing.

5. Connect from the other computer

Connect using the sharing computer’s 169.254 address from step 2, not its name. If both computers are also on Wi-Fi, the name can lead to the Wi-Fi address, and the copy runs over Wi-Fi instead of the cable.

From a Mac

  1. In Finder, choose Go > Connect to Server….
  2. Type smb:// followed by the address, for example smb://169.254.20.30, and click Connect.
  3. Choose Registered User, enter the user name and password from step 4, and click Connect.
  4. Select the shared folder and click OK. It opens in Finder.

From Windows

  1. In File Explorer’s address bar, type \\ followed by the address, for example \\169.254.20.30, and press Enter.
  2. In the Enter network credentials window, type the user name and password from step 4.
  3. Optional: select Remember my credentials.
  4. Double-click the shared folder to open it.

From Linux

In Files, press Ctrl+L, type smb:// followed by the address, and press Enter. Sign in with the user name and password from step 4.

Step-by-step instructions for each pair are in Mac to Mac, Windows and Mac and two Windows PCs.

After sleep, a restart or unplugging

Built-in file sharing doesn’t remember the cable connection. If either computer sleeps or you unplug the cable, the share disconnects, and copies in progress stop with an error.

  • After sleep or replugging: wait for the cable link to come back, then connect to the share again.
  • After a restart: connect again from step 5. On Windows, a mapped drive may report that it could not reconnect, because the cable link comes up after you sign in.
  • If the address changed: look it up again as in step 2 and connect to the new one.

For more, see why a network share disconnects after sleep.

If copies are slow

  • The copy goes over Wi-Fi. Connect with the cable’s 169.254 address rather than the computer’s name.
  • The folder has many small files. File sharing handles each file in turn. In our tests, a Mac’s built-in file sharing took almost four minutes to copy 20,000 small files over a 10 Gb/s cable.
  • Every request is signed. Windows 11 version 24H2 and later require SMB signing by default, which adds work to every request.
  • Defender scans each file the first time. The first copy of a folder of small files from a Windows PC waits for Microsoft Defender. See known issues on Windows.