14 week old lab has extreme biting problem,

Question
QUESTION: We recently adopted a lab/pit mix puppy from our local shelter. When we brought him home, after a few days we discovered he liked to bite--a lot. We attributed to teething and playfulness, however it's beginning to be a huge problem. His puppy teeth are very sharp and cause small puncture wounds and he doesn't understand that we want him to stop. We've tried redirecting his biting to toys, however he is quickly bored with them and then returns to biting us. We then moved to a very stern verbal "NO!" accompanied by a tap on the muzzle, however this gets him more excited. We then read  that grabbing his muzzle, along with the back of his neck until he whines works, however as soon as we release him, he is back to his biting antics. Then, searching a forum, we read that yelping or bellowing like a hurt dog and then ignoring him works, but that also excites him more. I'd also like to add that he only exhibits this behavior at home--whenever we are out somewhere, he is practically on model behavior. We are at our wits end and completely stumped as to where to go from here, and any advice would be greatly appreciated!

ANSWER: Young Labs, which I know best, and other puppies tend to very bad about biting. You see a litter of them, and all the ones that are awake are biting another one or themselves. I am not even sure they realize that when they are alone, if they quit biting, they would quit being bitten. At 3 to 4 months they are getting their adult teeth, and it seems they spend every waking moment biting or chewing. One thing you can do at that stage is to knot and wet a piece of cloth. Then freeze it. The cooling will soothe the gums. Only let the puppy have it when you are there to watch it. I maintain a Lab's favorite chew toy is another Lab. Otherwise they settle for any person they can. They keep hoping to find one that won't yelp, jerk their hand away, and leave.

Withdrawing your attention is a powerful tool, but it will take a while.  I think it is easier with younger puppies that have not had as long to reinforce it by playing with their littermates.

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QUESTION: This answer is wonderful, but unfortunately it is not helpful. I should have also added that we have also tried the frozen chew toys and we have also tried withdrawing our attention, which doesn't work either, as he bites any available spot on us as soon as we break eye contact. The only thing that stops him from biting us is putting him in a completely different room. However, we don't want to keep him isolated from us all of the time, and 15 minutes after we let him out of his little isolation room, he starts biting again. He also tends to bite my boyfriend more than he bites me, and he tends to be rougher with him. Is there any other advice that you could give me?

Answer
You have to understand the biting is a very natural thing, and the longer he was allowed to bite his litter mates, the more difficult it will be to stop it.  There is no quick, easy way.  He must lose your attention time after time and each and every time he bites.