From syncthing web I added a remove device which was offline: I had the device id and I put it in the proper place.
After that I defined a folder to syncronize with the remote device I had just created.
After a few seconds, the folder bar said (and still says) “Syncronized”. But the device never went online.
I thought it was a bug, someone told me it’s the expected behaviour.
Syncthing Version: v0.14.48, Linux (ARM) OS Version: debian (Netgear ReadyNas)