Adolescence is a time that gradually or perhaps overnight it will seem that your adolescent dog has forgotten all the important lessons you taught him as a puppy.
Adolescence and sexual maturity begins around five months and may continue for up to two years of age. You have put a great deal of time into puppy’s socialization and training for manners around food, greeting other dogs and people, bite inhibition and basic obedience skills. You have diligently worked to take advantage of the critical socialization period that exists up to twenty weeks of age. You knew his “puppy license” with other dogs would expire at about this same time.
Problem behaviors may begin with household etiquette (house training), basic obedience skills, impulse control, bite inhibition, dog–dog socialization and dog-person socialization. Your dog is now bigger, more physically competent, testing out relationships with other dogs and testing the limits of what behaviors work to his advantage. Up until now you were everything to your puppy, the source of all things good, food, fun and protection. Now your adolescent dog is deepening and broadening his interest in other things, other dog butts, urine and feces smells, scents of almost everything, horse-play with other dogs exploring the world with more confidence and independence. He will be less inclined to shift his attention to you when asked. That solid puppy recall may begin to breakdown during adolescence.
Your socialization job is not over.
Ian Dunbar writes, https://www.dogstardaily.com/training/ch-4-adolescent-dog-training-18-weeks-2-years
Puppy socialization was a prelude to your safe and enjoyable continued socialization of your adolescent dog. However, your adolescent dog must continue meeting unfamiliar people regularly, otherwise he will progressively desocialize. Similarly, successful adolescent socialization makes it possible for you to safely and enjoyably continue to socialize your adult dog. Socialization is an on ongoing process.
Walk your dog. Your dog needs to continue to meet other dogs, people, places, things and have new sensory experiences. Walks may be less enjoyable as your dog is drawn to further exploration and heightened interest in the environment. He is now bigger and is willing to test what he can get away with, with you.
Behaviors that are rewarded will be repeated, reward abundantly for your dog’s connection and attention on you.
“Even though” training
Suzanne Clothier writes https://suzanneclothier.com/article/even-though/
Create clarity in your expectations, one that helps him understand that while you recognize his needs, he needs to wait for permission from you. This is what I call "Even though..." training. It is amazing how fast dogs who have been labeled as "lacking self-control" calm right down and become quite cooperative when the handler can set clear expectations.