Mac computers sometimes have trouble establishing a connection with some of our switches. The solution is to change the connection speed of the Mac from 1000 to 100 Mbps. Below there are two sets of instructions to do that. One just shows the name of the menu entries that you would need to click, and the other is a graphical guide.
Apple Icon (on top left of screen) > System Preferences > Network > Ethernet> Advanced > Ethernet > Configure > Manual > Speed > 100 mbps
Duplex should always be set to "Full."