Great dog who needs time and patience

Brownie is a 3 year old shepherd mix–I’m assuming husky as he loves the snow and is an escape artist. He is neutered and up to date on all vaccines. He loves to be stimulated and loves to run and play ball. He is crate trained, and he knows his basic commands. High energy. Does well at dog parks once he warms up, but does not do well with other dogs if he is on a leash. He does great with my children and their friends but is wary of new people. No exposure to cats or any other animals. He does resource guard.