Troubleshooting

Almost every problem is discovery rather than transfer, so work through it in that order.

Devices do not appear

Are they on the same subnet? mDNS does not cross routers. Two machines on the same Wi-Fi name are not necessarily on the same subnet — guest networks and mesh systems often separate them.

Is client isolation on? Many routers, and most guest networks, stop clients from talking to each other. That blocks discovery entirely, and it cannot be worked around from the application.

Was the network permission granted? On macOS this is Privacy & Security → Local Network; on Windows it is the Defender Firewall prompt, which must include private networks. A declined prompt looks exactly like a network problem.

Is a VPN capturing traffic? A full-tunnel VPN will usually break mDNS even between two machines sitting next to each other.

They connect, but nothing is copied

Is it text? Only text is synchronised. Images and files are not.

On Linux, is the clipboard tool installed? xclip on X11, wl-clipboard on Wayland. Without it the application runs but can neither read nor write the clipboard.

Testing without a second machine

Two full clients on one machine will echo each other endlessly. The repository ships a helper that receives without writing to its own clipboard:

python tray_client.py     # the real client
python test_peer.py       # stands in for a second device

See Testing.

Logs

macOS keeps them under ~/Library/Logs/SharedClipboard.