DIAGNOSIS The router is not getting a valid IP address from your modem. The WAN port link is good, but authentication failed.
FIX Power cycle the whole chain. Unplug the router and modem. Wait 60 seconds. Plug in the modem, wait for its lights to stabilize. Then plug in the router. Use the short Ethernet cable from the box to connect modem WAN to router WAN port.
IF THAT DIDN'T WORK Your ISP might require MAC address cloning. Log into the router. Go to Advanced > Network > Internet. Set Internet Connection Type to your ISP type. Look for a "Clone MAC Address" option. Enable it. Save and reboot.
HEADS UP A solid orange Internet light means a physical link but no data. If it's flashing orange, that's a different problem—the cable or port is likely bad.