If the person before you had a static IP that doesnt match your network you will not be able to connect. The best way to go about this is to perform a factory reset. There is a pinhole next to where the ethernet cable plugs in, that is the reset button. Use a paper clip or something similar to push the button down and hold it for 5-6 seconds until you see it flash both the red and green light at the same time on the status LEDs. Once that is done give it about 2 minutes to reboot and it will be on DHCP with just the factory antpool configuration for mining. You should be able to see it on your routers DHCP table at this point and you can then access the GUI to complete the setup.