The number one thing that messes up tennis players at the net is their mindset. You don’t have to win the point on the first volley. You’ll be more successful at the net if you focus on hitting two volleys instead of one.
When you try to force a winner on the first volley, you usually go for a little too much and that’s where the swing happens. Instead, use your body to push yourself through with your hands and the racket way out in front. Anticipate a second ball coming back. You’ll be even closer to the net, which gives you less margin for error and more angles.