Rsync over SSH - cannot connect to remote

Hello!

I am trying to push data from a local ReadyNAS 202 to a remote ReadyNAS 102 accross the internet using a backup job initiated on the local 202.

I get "Unable to connect to host - 7077010011" if I test the remote destination connection.

If I run the job I get:

"Backup Status: Fail: failure during copy.

Failed to run rsync, return rc 65280 (255)
'rsync' command returns rc=65280

ssh: connect to host X.XXX.XX.XX port 22: Connection timed out
rsync: connection unexpectedly closed (0 bytes received so far) [Receiver]
rsync error: unexplained error (code 255) at io.c(226) [Receiver=3.1.1]"

(where X.XXX.XX.XX is the 102's WAN IP address).

Both NAS's are on 6.5.1. Both have SSH enabled.

I am able to log into the remote 102, both locally and across the internet, with pUTTY and an SSH user I have set up. This is the same SSH user I am trying to connect to run the backup job. I am able to log in using a public/private key combo, Shell Access is "allowed," "Rsync only" is unchecked, 

I have installed the public key for the 102 on the 202, both for the admin user and for the SSH user.

I have set up my router (a BT hub 3) to forward port 873 to the LAN IP Address of the remote 102. It is translating to port 22 on the 102.

The Destination part of the backup looks like this:

Type: remote

Name: remote: Rsync over Remote SSH

Host: X.XXX.XX.XX
Path: Documents/
Login: <SSH Username>

The overall SSH setting on both boxes is "Enable Password Authentication - No."

The "Documents/" share on the target 202 is set to "Allow Anonymous Access - Yes", "Everyone - Read/Write," no Hosts or DFS defined, and "Hide this folder: No."

I am totally stuck... any help is much appreciated!!!!