Network and discovery

Connection and discovery

Discovery uses mDNS on UDP port 5353. Transfers use QUIC on the UDP port announced by the receiver (4242 by default). Guest networks, Wi-Fi isolation, VPNs, or firewalls may prevent devices from finding each other.

A device does not appear

• Keep the receiver open and confirm both devices use compatible protocol versions.
• Confirm the devices are not on isolated or guest networks.
• Check that the firewall allows mDNS and the receiver's UDP port.
• Use --address in the CLI to separate discovery problems from transfer problems.

Virtual machines and WSL

Virtual network adapters may block multicast or make a guest unreachable from other devices. Configure the VM or WSL networking mode and firewall to allow mDNS and the receiver's UDP port. If discovery is unavailable, use the receiver address with the CLI.

Each environment has its own identity

Separate operating-system environments have separate Dukto identities, even when they share a hostname or IP address. Use a distinct receiver port when two instances run on the same machine.