I'm not quite sure what triggered it, but once I got to a certain AA build, I started getting packet loss on my WAN port, followed by a connection down/up after a while.
Long story (VERY LONG, involving installing Debian on a vmware machine and many firmware compiles) short, I finally noticed that my 1043ND was negotiating at 1Gbit... Putting my gigabit switch between the devices confirmed this.
I exchanged changed the crappy CAT 5 cable for a good CAT 5E cable and all is well.