Obedience outside of the house is curated and nurtured inside the house. A lot of practice needs to be put specifically into recall training, and following your command if you want to have a vizsla that actually listens to you when on a walk. There are so many exciting things for your vizsla to see, hear and smell when outside, so of course it's going to be extremely difficult for him to remember that he needs to listen to you. The more training you put in at home and in your yard, the more chance you have of him responding to all of your commands. This is a whole different article in and of itself!