Dell Inspiron 580 Ethernet connection question?

I have an Inspiron 580 that's currently connected to the internet using a Netgear WN2000RPT wireless router range extender. It connects fine wirelessly - just a little slow.

I wanted to see if I can connect an Ethernet cable from the Dell to the Ethernet port on the back of the router. I plugged it in both units but can't seem to get it to recognize the hardwired connection.

Any advice (I'm a total rookie - I know).

Thanks