1. Make sure the firmware is up to date and the same on both NAS's
2. Make sure both Hard-drives are compatible using this chart http://www.dlink.com/-/media/Consumer_Products/DNS/DNS%20320L/Additional%20Downloads/DNS_320L_LW_Compatibility_List_20150122.pdf
3. The remote backup server password must be the same on both NAS's
4. Make sure the following ports are being forwarded (22 for SSH) and (873 for RSYNC)
5. When it asks you for the Remote IP, enter the other NAS's ip you use to login to it online with and the password is the password you entered into the server area that is the same on both NAS's
6. When port forwarding make sure the IP you use is your LAN address and it will always start be something similar to this 192.168.1.XXX