Sync over LAN without Internet

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?

Edit device, Advanced tab.

Should I use this or remote devise address / hostname? https://docs.syncthing.net/users/config.html