@nuttall Thanks for your response!
That makes sense. I don't care whether COMPUTER-1 and COMPUTER-2 sync directly (which is perfectly fine when they are both online at once) or via ALWAYS-ON-COMPUTER as the middle-man. If I understand correctly, the Read & Write key would somehow connect COMPUTER-2 to both ALWAYS-ON-COMPUTER and COMPUTER-1, such that it would sync with either one (or both) that is online?
Is there any reason I couldn't take this setup one step further and do something like the following?
COMPUTER-1 [using Read & Write key, and configured only to sync over LAN -- no Relay or Trackers]
ALWAYS-ON-DEVICE-1 (e.g., Raspberry Pi) [using Encrypted key]
COMPUTER-2 [using Read & Write key, and configured only to sync over LAN -- no Relay or Trackers]
ALWAYS-ON-DEVICE-2 (e.g., Raspberry Pi) [using Encrypted key]
The idea would be that COMPUTER-1 would do fast LAN sync with ALWAYS-ON-DEVICE-1, and COMPUTER-2 would do fast LAN sync with ALWAYS-ON-DEVICE-2, and ALWAYS-ON-DEVICE-1 and ALWAYS-ON-DEVICE-2 would sync with each other (to pre-download content to each location to be ready for fast LAN sync when the computer is connected at each location). Would that work, or would ALWAYS-ON-DEVICE-1 and ALWAYS-ON-DEVICE-2 not be able to sync with each other if they both use the Encrypted key?
Another probably dumb question:
If I want to sync, for example, my large Photos folder between COMPUTER-1 and COMPUTER-2, could I pre-seed the two folders by copying them manually by USB (so they start off with the same contents so I don't have to sync over the Internet many, many GBs of files)? Could I do that by first creating the Sync on COMPUTER-1 and copying the Read & Write key to COMPUTER-2 and specifying the location on COMPUTER-2 as the identical Photos folder?