First of all Spidey, welcome aboard. I think you'll find us a friendly and hopefully informative lot.
But I fear you have come up with a poser here.
Frankly cannot stand hard boiled eggs. If there is a he!! (they hate us using that word on this forum, people are very polite here) there will be waiters carrying fancy trays serving nothing but hard boiled eggs. Blechhhh.
But I will make them for others, even though I cannot stand the smell.
And think I make a pretty good deviled egg.
I know there are many ways to boil the suckers. I usually put them in a pot, bring it to a boil, shut off the burner and leave them covered for fifteen minutes or so. Then I shock them.
Boiling eggs for fifteen minutes to me seems a bit extreme, just my humble opinion, but I assume you are an old hand at boiling eggs and this is a first.
All I can suppose is that you got a batch of bad eggs.
Not much help I know but until someone comes up with a better suggestion that is all I can come up with.
Again welcome to the site and hope we see more of you.