You don't need to sync every folder to every device. Each instance can choose which folders it wants to sync. Plus there are several folder types, particularly

You don't need to sync every folder to every device. Each instance can choose which folders it wants to sync. Plus there are several folder types, particularly send or receive only. See https://docs.syncthing.net/users/foldertypes.html https://docs.syncthing.net/users/foldertypes.html However,it's not a cloud backup service. If you need online storage then best option is to get an online service.