How do I check what Ethernet speed my device has negotiated?
Windows
Open the start menu and search for Control Panel
Click Network and Internet
Click Network and Sharing Center
Click Change adapter settings
Right click the Ethernet interface you’d like to check and click Status
To the right of Speed you should see the speed your Ethernet interface has negotiated
Apple Mac
Open the Network Utility application on your Mac, located in Applications > Utilities > Network Utility (you can also search for Network Utility in Spotlight)
In the Info tab, under Network Interface, use the drop-down menu to select your Ethernet interface
The Ethernet speed appears in the list of interface information, along with other information (like your IP address).