I have exactly the same problem, but it doesn't look line anyone here has the solution.  What great support!  :\

By George, I think I've got it!  (Well, I've narrowed it down anyway.)  So, I've got an RVS4000 with firmware version V2.0.0.3 and I've been trying to do a similar thing:  I have a NAS sitting on my local LAN with a horribly insecure FTP server on it...