I'm having the same issue. I pay for 200mbps but only getting about 30mbps. I called support and they couldn't figure it out. They're going to have a new kind of router sent to me. Hopefully that helps
cable guy came out and tested everything. He determined the problem was the wiring that runs from their box next to the street all the way into my apt building. He says it's so old it has degraded to the point that it's interfering with the signal coming through.
it was a bigger job than he expected, but he replaced the wire that comes from the into the apt. After setting everything back up, I'm now getting a little over 200mbps
so if you have the same problem , have all wiring replaced all the way to the street. At first he was reluctant to do it, but then decided to just get it over with. Great guy