R6300 not detecting internet

Hi,

Would appreciate getting some help please with my R6300 Netgear router. It's a second hand router I purchased and was told by the previous owner it works fine. I'm trying to connect it to fibre through a modem (Optical Network Box) and I can confirm this works fine as I have the standard free router provided and that connects fine. So I'm certain it's some setting within the Netgear router that's causing this.

So, I started by completing a factory reset, waited for the power light to blink and I can confrm it was successful as the SSID network returned to it's default name. I also completed a manual upgrade of the firmware. My issue is that when I try to connect wireless or ethernet cable, I get no internet. The light I have noticed on the internet shows solid amber. I was told this needs to be green in order for it to work. What I did test by logging into the router page, was if I setup the IP address, gateway and DNS servers manually then the light switches from solid amber to green but still I get no internet.

I tried power cycling, testing WAN ports and still getting no luck.

Appreciate any advice or assistance to help me with this.