Comment by sp332

DOCSIS 3.0 modems support at least 171 Mbit/s https://en.wikipedia.org/wiki/DOCSIS#Speed_tables But you have to share those channels with your neighbors, and then you have to share the back-haul lines with lots of people. So no, you don't get to use all the available bandwidth, but I don't think Comcast ever pretended that they weren't limiting you. If you upgrade to faster service they just click a button to bump your allotted speed up.