FTP error 553 Users may not upload files

I have both a PR4100 and a PR2100. We have an FTP utility that does not seem to be able to download files to either of our systems. If I manually use FTP from my PC this is the error I get. If I CD /MO (MO being a folder in the root directory) I can put the data into subfolders even two levels deep. Why do I have to manually make the first hop? (This option is not available on our FTP utility.)
Thanks.

Hi,

You could refer to the following link: My Cloud: Configure FTP Downloads App