Speed test tool value low

I submitted this to CF support but they directed me here!

I have run a few tests via the CF speed test tool and although it is awesome compared to others, it never reports more than 100Mbps despite us being connected to the Internet via a 1 Gigabit leased circuit. Am I missing something here? Is the tool broken, or reporting wrong? I can do an Ookla test immediately after and get symmetrical throughput of approx 980Mbps.

Thanks