The problem for which I posted is solved just a couple of hours later. I could control /limit speed for a ftp server for a specific device connected to the router. Typically, that device used to get 5MBytes/s, now after reshaping the bandwidth i'm able to render only 250KBytes/s..
The settings i added was in the traffic shaping option... I has the option of Source ip and destination IP for which i want to control bandwith.. The speed that is controlled is only for that specific device and for a specific website... Now as the problem is solved i'd like to share it with others who also want to employ such settings..