Yes, it needs an exernal server. By default, Syncthing is pre-configured with community-hosted discovery servers: - https://github.com/syncthing/syncthing/blo

Yes, it needs an exernal server. By default, Syncthing is pre-configured with community-hosted discovery servers: - https://github.com/syncthing/syncthing/blob/master/lib/config/config.go https://github.com/syncthing/syncthing/blob/master/lib/confi... The community also hosts relay servers, so if your two devices can't communicate with eachother directly, it will work anyway. Relay servers take bandwidth. Anyone can run a relay server, and it will automatically join the relay pool and be available to Syncthing users. This is documented here: - https://docs.syncthing.net/users/strelaysrv.html#strelaysrv https://docs.syncthing.net/users/strelaysrv.html#strelaysrv It would also be possible to host your own private relay and discovery pools, if you need that for some reason.