It's not something you can fix, except to find a new ISP. ISPs, especially crappy ones like Comcast and Charter, tend to oversell the bandwidth they have available in any given area, which is why you're seeing a degradation in upload speeds. Ideally the upload/download is symmetrical, but rarely will you see that except in business packages and dedicated lines. Beware any ISP that sells internet packages with a upload speed that's less than 1/3 the download speed. It means they've already overloaded their infrastructure and their service will only get worse as time goes on. All the focus goes to download speed in those situations. You can demand a refund for them not providing the bandwidth they sold to you, but I doubt that will get you anywhere.