I had a similar issue this weekend. Once I changed my Apple ID password I started to receive SMS messages from people with iOS devices. I had to re-authorize all Apple services on my other devices and machines.
FYI mrsync is confusingly named since it doesn’t actually use the rsync algorithm it performs multicast file transfer. (The whole file is sent not just the deltas).
I’ve always thought it would be cool if someone added rsync capabilities on top of bittorrent. I’m not sure Etsy would see any benefit but I bet Twitter with their murder server deploy would.