I've looked up so many ways to try to fix and 80151911 error, I've tried everything. Nothing works, my internet is perfect and it still continues to not work. My Xbox takes up to 10 minutes just loading for me to pick my profile than another 10 minutes to sign in, which after those 10 minutes it just says, "Fail to sign in" anyways. Only had my Xbox for less than a year, I take perfect care of my Xbox and this is still happening and It just does not work no matter what I do. I've been really frustrated because every time I play a game my Xbox freezes and it takes up to and hour and a half before it works and I can play again.