private void Box_Network_Digits_3_TextChanged(object sender, EventArgs e)
 {
     if (Box_Network_Digits_3.Text.Length >= 2)
     {
         Box_Network_Digits_4.Focus();
     }
 }
 private void Box_Network_Digits_4_Click(object sender, EventArgs e)
 {
     Box_Network_Digits_4.Focus();
     Box_Network_Digits_4.SelectAll();
 }