I used to fear the volley and Net game, and did not make clean contacts for a few years.
Recently, a new coach changed me with a simple drill and advice. Just keep the hand STRAIGHT IN FRONT, on both backhand and forehand volley all the way, and DO NOT MOVE/ ACCELERATE the hand. Just use the leg to move up to the ball, while keeping the hand fix. After few sessions, it totally changed my volley.
It fixes 2 mistakes of mine: 1) Bend elbow (not firm resistance to incoming balls) 2) Too much racquet head movement (bad timing).
After you get comfortable with this drill, you can start accelerate racquet a little bit for more speed. Otherwise, just learn to use the leg
Try it and see if it works for you.