Firware OS5 and Rsync

Would like to see a solution for backing up using to RSYNC from another platform e.g. QNAP or similar WD platform e.g. with different firmware versions to the WDEX2Ultra fimware or higher. At the moment I cannot use the root password from the WDEXUltra when I want to establish an Rsync connection. But I also cannot make a remote backup between two WDEX2Utra’s with firmware version 2.40.175 and 5.06.115 on the same LAN. As long as there is no solution For Rsync, I cannot upgrade my WDEX2Ultra to firmware Can access the WDEX2Utra’s via SSH but with Firmware I can’t find a file in / var / run / Something is blocking the creation of the file or it
is in a different location? Has anyone more information about Rsync or WD’s remote backup?