It's really weird. This article contains the sentence

> At just 18 years old Gauss used a heptadecagon to solve a classic problem that had stumped mathematicians for more than 2,000 years.

where the words "stumped mathematicians" are hyperlinked to the article "Prime Number Puzzle Has Stumped Mathematicians for More Than a Century" that you're talking about, even though there's no real connection at all between the problem Gauss solved and the one Yitang Zhang worked on -- they've just linked the two because of the word "stumped" it looks like. (Well prime numbers turn up in both but the problems are not really related beyond that.)