2d collision with "unwalkable" objects

Hello everyone.

I'm working on a 2D collision script inspired from this tutorial.

I have a player controlled with the key up, down, right and left, and a gameObject with the layer "unwalkable" (layer number 8). What I want is simple: when the player box collider hit the unwalkable box collider, the player is stopped.

I have two problems: Currently when the player hit the unwalkable object, he's stopping... but not always. For example when the player's bottom hit the unwalkable's top, the player run through it:

Both box collider should not superimposed.

The second problem: for example the player is moving to the top and hit and object, so the player is stopped. But when the player is hitting the object while moving top-right or top-left, he run through it.

Here's an extract of my code:

 private RaycastHit hitInfo;
 private float halfMyX = 18f;
 private float halfMyY = 24f;
 
 private int unwalkable = 1 << 8;
 
 private float absVel2X;
 private float absVel2Y;


 public virtual void characterMove()
     {
         speed.x = 0;
         speed.y = 0;
         
         if (up)
         {
             speed.y = charSpeed;    
         }
         if (down)
         {
             speed.y = -charSpeed;    
         }
         if (right)
         {
             speed.x = charSpeed;
         }
         if (left)
         {
             speed.x = -charSpeed;    
         }
         
         checkBlocked();
         
         speed2 = speed * Time.deltaTime;
         transf.position += new Vector3(speed2.x,speed2.y,0f);
     }

 public void checkBlocked()
 {
     absVel2X = Mathf.Abs(speed2.x);
     absVel2Y = Mathf.Abs(speed2.y);
     
     // blocked right?
     if (Physics.Raycast(new Vector3(transf.position.x,transf.position.y,transf.position.z), Vector3.right, out hitInfo, halfMyX+absVel2X, unwalkable))
     {
         if (currentFacing == direction.right || currentDirection == direction.right)
         {
             speed.x = 0;
         }
     }
     //blocked left?
     if (Physics.Raycast(new Vector3(transf.position.x,transf.position.y,transf.position.z), -Vector3.right, out hitInfo, halfMyX+absVel2X, unwalkable))
     {
         if (currentFacing == direction.left || currentDirection == direction.left)
         {
             speed.x = 0;
         }
     }
     //blocked up
     if (Physics.Raycast(new Vector3(transf.position.x,transf.position.y,transf.position.z), Vector3.up, out hitInfo, halfMyY+absVel2Y, unwalkable))
     {
         if (currentFacing == direction.up || currentDirection == direction.up)
         {
             speed.y = 0;
         }
     }
     //blocked down
     if (Physics.Raycast(new Vector3(transf.position.x,transf.position.y,transf.position.z), -Vector3.up, out hitInfo, halfMyY+absVel2Y, unwalkable))
     {
         if (currentFacing == direction.down || currentDirection == direction.down)
         {
             speed.y = 0;
         }
     }
 }

Here's how the script works: - If the button "up" is pushed, the variable "up" is true. Then the speed is increased. - The checkBlocked() method is called. It set the speed to 0 if the player collide with an unwalkable object.

I could not found a solution for this two problems, maybe I don't know where to search (I tried to find an example of script doing what I want, witch is, I guess, a basic thing...).

Does someone have a solution?

Thank you for your time!