Internet orange light on router

Today my Internet went down completely without warning. At first I thought it was an issue with the ISP and called them. There is no fault with my cable modem (Motorola SURFboard SB5101) or with my connection as I have Internet connection when I connect the modem directly into a PC.

If I connect the modem via Ethernet to the WNDR4500 router, the orange light comes on for the Internet. I have tried restarting the modem + router and resetting to default settings