I use my n5200 to backup other hosts including a Synology NAS using the rsync daemon on the n5200. Synology uses BusyBox linux. But my Windows machine showed the n5200 backup files as hidden. After much trial and error, I determined that -rwxrwxrwx permissions on the n5200 caused this condition and removing the "others execute" permission corrected the problem (should be -rwxrwxrw-). I was also able to uncheck the "hidden" attribute in Windows after I changed file ownership (by using PuTTY to log into the n5200 as sys and using linux commands) to agree with the same username Windows used to access the N5200. Finally, I was able to set up the rsyncd configuration file to backup the Synology NAS with the desired ownership and permissions.
This seems to be a Thecus software issue because ths Sunology NAS has no issues with the -rwxrwxrwx permissions