send and receive only are purely local settings. The other devices don’t know, that this one is “send only” or “receive only”.
On every index change (e.g. local file change), the device sends the new index to all other devices. Those devices then decide, what to do with that information, e.g. pull the new data from the devices which have it.
Thank you very much, this helps me to understand more about the functionality of Syncthing.
What is a index you mentioned?
What is the meaning of a index information, indexing, local index and index database? I’ve read about this in the documentation but couldn’t understand it.