Do you have to upgrade across all your syncthing instances at once, or will 1.x be able to talk to 2.x for a while without breaking? It seems like a pretty big update and I'm not sure what I need to think about if I'm upgrading
“Syncthing version 1.x will soon be replaced by Syncthing version 2.x.
Version 2 brings a new database format and various cleanups, but remains
protocol compatible with Syncthing 1.”