Is it possible to use Syncthing over the LAN (and across VLANs where discovery broadcasts not allowed) without Internet connection? How Syncthing devises discover each other?
By discovery broadcasts and announcing to a default global server. So you’ll need to manually enter ip addresses or setup your own discovery server inside the LAN.
Where can I enter ip addresses?
Should I use this or remote devise address / hostname? https://docs.syncthing.net/users/config.html