I think that as you are only on night 4, he is still trying to adapt from being away from his brothers/sisters - after all he has been with them 24/7 for the past 12 weeks.

Our choc lab is now 9 weeks and we've had him for just over a week now, the first 3 nights in his crate were hard as like your pup all he done was whine for a while but he soon settled down. Give it another few days and I am sure after this he will be much more settled at night.

Do you leave him alone in his crate during the day? Maybe try doing this for 10 mins or so at a time, start off near him where he can see you and then get further away each time - this may help him adjust to it before night times!

HTH

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