Stopping my player from moving when hitting a wall.

Hello Leroterr

You don't need to increase mass. Just add rigidbody to your player and collider. and add collider to wall. and put script on player which detects collision and perform action using that.

//This is for 3D game in C#

 void OnCollisionEnter(Collision collision) 
 {
         if(collision.gameObject.name == "YourWallName")  // or if(gameObject.CompareTag("YourWallTag"))
         {
                     rigidbody.velocity = Vector3.zero;
         }
 }

OnCollisionEnter doc

A surprising good method is actually moving your move script to a FixedUpdate and using rigidbody.position.

try this

 void FixedUpdate()
 {
     float x = Input.GetAxisRaw("Horizontal");
     float z = Input.GetAxisRaw("Vertical");

     playerRb.position += z * transform.forward * Time.deltaTime * speed;
     playerRb.position += x * transform.right * Time.deltaTime * speed;
 }

 it works perfectly :)
 
 void LateUpdate()
     {
         //fix flying if is blocked on jump
         if(charController.velocity.y == 0)
         {
             moveDirectionSmoothly.y = charController.velocity.y;
         }
             
         //fix "walk stopped" (stop the character if it is blocked by a wall)
         if(charController.velocity.z == 0)
         {
             moveDirectionSmoothly.z = charController.velocity.z;
         }
     }

Make the wall's rigidbody Kinematic. Then make sure the player's collider doesn't have a bouncy PhysicsMaterial.