You might be using new puppy gear
If your puppy has never worn a leash before, or you are using a new collar or harness, then there is a big chance your doggy wouldn’t understand how to move or walk in the equipment you just put on him.
According to Nicole Ellis, a certified professional dog trainer, when dogs feel a new collar or harness around their nick, they feel unsure how to move. Try to leave him on a leash indoors, when he eats and when he plays. He will soon get used to it and feel safe wearing it.
It is a new experience
Our world is full of interesting smells, sights, sounds, and stimulation, which could make your puppy hesitant to come closer. Since your dog’s senses are way too strong, he may start feeling overwhelmed as he is scared to move towards the big world.
Try to use treats and a lot of praise in order to get him excited for a walk.