I understand that you are having some issues trying to control the upload / download rate.
If you want to control the bandwidth usage, you'll need to check your router settings, however, we cannot provide you with this information since we do not handle it. In that case, I recommend you contact your ISP / router provider in order to know how to.
Since you are using the web-based application, you can try to adjust the bandwidth using the "Quality" feature, which is located next to the "Streaming speed" feature at the bottom of the SlingPlayer screen. If you do not know how to locate it, make sure to check this link.