The bronze snake in numbers and the serpent Lucifer

In Numbers 21:4-9, Moses makes a bronze serpent on a stick to heal the Hebrews' snake bites, as per God's instructions. They don't worship it, but they are to look at it in order to live. Why did God order a statue of a serpent knowing very well that a serpent is used to refer to Satan himself(Genesis 3:1)??? Help me understand the connection between the serpent used by God and the one symbolising His adversary...