final edit: Maybe my issue was really just IPv6 like others are taking about. I have CenturyLink fiber with the ONT directly connecting to the N66u and have had the 6rd tunnel they support setup. Disabled the 6rd under .57 an hour ago and haven't seen any connectivity exclamation marks or odd...
Should be easy to setup under the IPTV tab... see how I set it up on my N66U with a few screenshots linked to here. heh, and that screenshot was also posted in the comments of what you linked to, by me.