The second port is a pass though port. So if you had something already using an ethernet connection where you're putting the HR22 just move the cable to port one on the HR22 and then put a new cable between the HR22 and the device that was already there.
Being a Directv Noob do you just put the Network cable in the top one and it will cover both Direct2PC and Ondemand? Mine has been flaky on downloading. It updates the content but crashes(Goes to Pause) on download. I have downloaded Shows and movies. Also now it doesnt always see my Reciever on Direct2pc or can't view protected content on everything.