Connect with a standard Category 5 (CAT5) (CAT6 for Gigabit Ethernet) or better Ethernet cable to your local Network or directly to your Computer. When you power up the device, it attempts to initiate a DHCP network connection (standard configuration). If the device cannot initiate a DHCP connection (eg if you connect to your PC directly), it connects to the network with a link-local IP address with the form 169.254.x.x.
If your board does not have a Ethernet connector, (eg ZSOM-mini) you can build up a Ethernet via USB connection.
To reset the Network settings, follow the instructions here