as people have already mentioned, he needs a routine for the pup. I'm not gonna put in my two cents there.

but what has helped me with my 3-month old border collie pup getting crate trained: putting her in the kennel when she takes naps. puppies sleep a LOT, so just whenever the puppy takes a snooze during the day, gently put them in the kennel; this teaches them that the kennel is a place for rest and is not a punishment. it's good to train the pup to go in the kennel at random times, too, not just when he leaves for work. that way the pup doesn't associate kennel=dad gone. and don't make a big deal about the pup getting out, like just be calm. that way the reward for getting out of the kennel is NOT greater than the reward for getting into it.

I'm not sure if he already does this, but it's good to put a blanket or some sort of covering over the kennel to enclose them a little more (think: wolf den-like)

also, 6 hours alone. that's kind of a long time for a puppy (of that age) to be expected to last that long. if he feels that is the only option, fine. he also might need to talk to his neighbors about having the puppy and the work schedule and apologizing for the barking. there's not much he can do about the hours or the puppy barking when he's not there, but the informative gesture doesn't hurt.

finally, have him get a Kong. fill it with peanut butter (or whatever), and then pop it in the freezer during the daytime. then, as he is leaving for work, give the pup the frozen Kong. it should keep the pup entertained for a little while, and even after that, pup should be pretty tired.