My DGL 4500 has been working perfectly for about 2 years. I bought it specifically because I was adding a second Xbox gaming console to the house and my old router could not handle more than one. I have played Modern Warfare 2, Black Ops and Battlefield 3 with no connection issues (at least none that could be blamed on the router).
However, when trying to play Black Ops 2 on both consoles at the same time, one console often (but not always) shows a moderate NAT. The connection in the game has been pretty atrocious since yesterday. I am not entirely sure whether there is something wonky with my service from my ISP, or whether Black Ops 2 has certain port requirements that previous Call of Duty titles didn't require. I will have to do some more digging.
Many thanks to those who know their stuff who participate in the forum. I appreciate it.