Initial setup
Access new box through browser at find.synology.com, this will let you work through some simple setup steps to create the disk volume(s) and setup the admin account.Through the browser interface, create users, turn on home directories for users, enable SSH/rsync services. Enabling firewall is done through the browser interface, as is enabling holes in the firewall for SSH and rsync.
Synology SSH setup
Once that is done, I was able to SSH to the Synology as admin, but not users.Seems Synology boxes only allow admin account to SSH into the box.
I created keys and added to authorized_keys as usual.
I added auth users line to /etc/rsync.conf per instructions here:
https://rsync.samba.org/ftp/rsync/rsyncd.conf.html
Turns out, the auth users in /etc/rsync.conf was the key, until I did that, just got refused connections from the Synology box
During my fiddling, I found systemctl doesn't work to restart sshd as my other Linux boxes, this did....
synoservicectl --restart sshd