I'm about to dust off and drag out my old D-Link router that the Asus replaced; it should still be configured exactly how I left it when I unplugged it a couple years ago. Never had DDNS issues with it. I suppose if it works then maybe something's wrong with my N66U or perhaps firmware issues. But if it also doesn't work, then I'm lost, and all I can think of is something my ISP is doing...