If Arlo still cannot discover your base station, check the color of the Internet LED on your base station:
If the Internet LED does not light after two minutes, the base station failed to connect to your router. Unplug and re-insert both ends of the Ethernet cable connecting your base station to your router. Make sure that your router is powered on.
If the Internet LED lights solid amber, your base station is connected to your router, but is unable to connect to the Arlo cloud server. Make sure that your router is powered on and connected to the Internet.