Question : broadcom netxtreme 57xx gigabit controller

I have a broadcom netxtreme 57xx gigabit controller  capable of speeds up to 1000 mbps, i have cat 6! cables and i have a D-Link Di-784 router that is set to 100 mbps. How come when i go to "my network places" and go to "internet connection status" it says under "internet gateway status: connected, speed:  10.0 Mbps!??? not 100 mbps like it should be ?? why does it say 10 is my capable limt? how can i change it to 100 mbs?

also i have done some diagnostics at my isp site and i get the following response:
"Your modem appears to be connected to your computer via a 10 baseT Ethernet port. A 100 baseT Ethernet connection is required to ensure maximum connection speeds. Please replace your Ethernet port if you want to achieve download speeds approaching the full 15Mbps offered by Optimum Online.
but isnt a  broadcom netxtreme 57xx gigabit controller a 100baseT connection and even greater?

Answer : broadcom netxtreme 57xx gigabit controller

Some broadcom cards have trouble with automatic speed negotiation.  Go to the properties of your card, and lock it at 100mb. Full duplex will probably work, but if not , try half duplex.