I found this post useful to my debugging, but it did not contain my answer, so I am posting what I have learned to resolve the same issue.
Often, during storms, Comcast internet will go out on me. Basically, what they do is to effectively re-provision the service. Now the problem with that is during the "troubleshooting" they often get you to remove the router altogether, find the PC still does not connect, then then reset the modem and collect your PC's MAC addr (automatically), which they use to re-provision.
The key for me was that once I understood that, I used the D-Link feature to "copy pc mac addr" to the router and then the router could get a DHCP address from the pool. I verified that using other mac addrs, like the native mac on the router did not work, nor would any other PC mac i had in the house.
So, faking my router's MAC to look as if it were my PC's MAC addr, it got the WAN connection and then everything else on my network was OK. I post, hoping that this helps someone else in the future too.