If the network light isn't lit, that's a physical problem : The network of the gateway is not detecting a link. That's a separate issue to anything configuration related with your computer, etc.
First things would be to check:
I can't tell from your picture if the gateway is connected to a network switch, or direct to your PC
PC direct connection may not always work; connect to a network switch, to a known working port
Try swapping the cable
If you still get no network light, it sounds like a hardware fault and would need repair.
