Puppy training

Looking for tips and tricks on keeping a new puppy quiet at night. He’s 4 months old and we’ve had him for 2 nights so far. The first night he slept thru the night in his crate but last night he woke up barking like crazy at about 3am then again at 7:30am. I worry that our neighbour is going to complain as we live in a townhouse and they complained about our AC unit in the summer time.

I checked our security camera and it looks like our pup only barked for about 15 mins total in the night so it wasn’t too bad. But loud enough to have me worry and anticipate a nasty note from our neighbours.