I just now modified the /etc/rsyncd.conf file as per Dan Kozak's instructions. The old conf file is still there with the file name appended with today's date.

I then enabled the rsync daemon to run on boot using 'enable'. I'll ask Dan to start the file transfers again and see if this works.

controls@nodus|etc> sudo systemctl start rsyncd.service
controls@nodus|etc> sudo systemctl enable rsyncd.service
Created symlink from /etc/systemd/system/multi-user.target.wants/rsyncd.service to /usr/lib/systemd/system/rsyncd.service.
controls@nodus|etc> sudo systemctl status rsyncd.service
● rsyncd.service - fast remote file copy program daemon
   Loaded: loaded (/usr/lib/systemd/system/rsyncd.service; enabled; vendor preset: disabled)
   Active: active (running) since Mon 2020-04-13 16:49:12 PDT; 1min 28s ago
 Main PID: 4950 (rsync)
   CGroup: /system.slice/rsyncd.service
           └─4950 /usr/bin/rsync --daemon --no-detach

Apr 13 16:49:12 nodus.martian.113.168.192.in-addr.arpa systemd[1]: Started fast remote file copy program daemon.
Apr 13 16:49:12 nodus.martian.113.168.192.in-addr.arpa systemd[1]: Starting fast remote file copy program daemon...