So if you have one of those and are having this problem, Blizzard has at least identified the cause. They say they're working with the router manufacturers to come up with a fix, but if there really is a problem in the router itself, odds are Blizzard won't be able to hotfix it on their site, so you may have to go to the router's manufacturer for a fix (all that information, when it becomes available, will likely be on their site).
I am surprised, however, that this problem didn't appear before now. Blizzard says that the most recent patch (would that be 2.3.3 and the improvements to load time?) is responsible for "revealing a bug in the hardware," so if the router manufacturers don't release a fix, Blizzard may have to reverse whatever changes were made. At any rate, a fix is coming, no matter where it comes from.