rsync protocol incompatibility
Solution 1:
The FreeBSD box has a six-year-old version of rsync which uses an older protocol version. You can force the new version of rsync to use the old protocol by adding --protocol=29 to your rsync command.
Solution 2:
Interestingly, putting an intermediary machine between origin and destination machine achieves the desired result:
ie.
machine 1 (origin) >> machine 2 (intermediary) >> machine 3 (destination)
machine 1: rsync version 2.6.8 protocol version 29
machine 2: rsync version 3.0.3 protocol version 30
machine 3: rsync version 3.0.7 protocol version 30