Issue Setting up Airport Time Capsule

Hi All,

My friend who upgraded to the new Airport Time Capsule just gifted me his old one A1408. I followed the setup instructions, plugged to my Comcast Modem TC8305C (router is bridged). I reseted the router according to the instructions here. Internet is working perfect, I have my workstation plugged directly to the modem and I want it like that. I also plugged the Airport to the modem, however it doesn't get signal and I get the amber intermittent light. My friend mentioned to have the Airport as the only thing plugged to the modem....however, I want/need the workstation plugged directly, besides that's the way I had my Linksys E3000 and it worked fine (weak signal).

Airport Utility is installed in another computer, a Macbook Air (ElCapitan 10.11.1), that I plugged to the Airport, but it doesn't recognize any Airport plugged.

What did I do wrong. How can I make it work?

I appreciate the help.