OS X El Capitan: Use Network Utility to check your network connection
Network preferences indicates the status of your network connections, but you can also use Network Utility.
You can use Network Utility to view each network connection, including the hardware address of the interface, the IP addresses assigned to it, its speed and status (active or inactive), the name of its manufacturer and model, a count of data packets sent and received, and a count of transmission errors and collisions.
Open Network Utility.
Click Info, then choose a network interface from the pop-up menu.
Use this information, together with network information provided in Network preferences, to investigate your network connection.