I understand how having your streaming slowed down can be a frustration. I am not an expert on internet service or how they go about increasing or decreasing bandwidth speeds. What I do know is that the more you use your network's connection it slows down the bandwidth speeds. So say you have numerous devices or computers streaming from your router, your bandwidth will now be lowered. A quick tip way to reset it & start your bandwidth off from scratch is to power cycle the router. Which is nothing more than unplugging the router & plugging it back in again.
You also want to check the speeds of the network you are connected to. That could play a major part in how good of a stream you are getting. In order to check your speeds, you could go to the link below to do so.
I hope this information will aid you in getting this issue resolved!
The Sling Moderation Team