Do you want to know your system NIC card (LAN Card) supporting speed just follow my steps
- Go to the Control Panel".
- Select "Network and Sharing Center".
- On the Left panel select "Change Adapter settings"
- Right click on the "Local area Connection" and select "Properties".
- In the "Local Area Connection Properties" window select the "Configure" button.
- Select the "Advanced" tab.
- In the scroll list of options find "Speed & Duplex" or "Link Speed & Duplex" and select it.
- The NIC speed will be displayed in the "Value" drop down menu.