Hi, I did try this but it made no difference. I opened tcp/873 from the public IP of the hosted DSS and pointed it to the internal address of the source DSS. I am a Cisco Certified Network Professional, so I am pretty sure that I know how to this.
I would be grateful if you could explain why the destination DSS needs to initiate a connection to the source DSS when it is the source DSS that is pushing data to the hosted DSS?
As also stated, I already use rsync for backup of linux internal servers to hosted servers without any problems.
The Destination does not need to initiate a connection. If your able to see the Shares of the Destination and your Snapshot is assigned to that NAS Logical Volume then it should work as it is that easy as you have it setup on the other servers internally.
What does the rsync logs say on the Source server? We might want to see the logs from both systems so you might want to submit a support ticket.