Hi

It took us about a month to get Rohan to sleep in his cage without howling for at least an hour first. Not fun wehen you and the neighbours are deperately trying to get some sleep!
He is just under five months now and he will go in his crate to sleep during the day without being guided and is quiet when we are out and at night.

I'm not sure what finally did the trick it may just be that he was getting older but we changed from putting a kong in with him to just sitting next to his crate at night time until he lay down to sleep properly. It usually took about 10 minutes of sitting in the dark not talking or giving him attention but just so he knew we were there, so not much fun but worth it. I'd say we did it solidly for about a week and a half and now he just gets in when we say bed time.
The kong just distracted him for ten minutes then the noise would start, plus he's be full of energy from whatever we had stuffed it with.

When we leave him to go out I also say' won't be long' so he associates it with me leaving and pop a couple of treats in. Again we keep a specific treat for when he's being left alone ( puppie markies) rather than usuing the same for everything. Again in the hope the puppy associates it in his head.

Might be worth a try?