said by RRedline:SATA-3 is 6Gb/s, not 600Mb/s. All of my SSDs have no issue reading and writing a sequential file at much faster than 1 Gb/s.
I don't think it's unreasonable to suggest that he may have hit a bottleneck outside of his Internet connection. Almost any PC can fully utilize 100 Mbps, but 1 Gbps? Not likely. Even SSD's can't read/write at that speed, and most PC's out there don't even have SATA-3 to support 600 Mbps, let alone 1 Gbps.
Even so, once you have multiple devices using an Internet connection, it doesn't matter what a single device can handle. It's amazing what it possible now compared to just 10-15 years ago.