How to generate the Top and Right border for my game's arena?

Hello, I am relatively new to C# and Unity as a whole and am making a game involving randomly generated boards of different sizes. However when I generate the board the Left and Bottom edge generate fine whereas the Top and Right do not generate at all.

I believe the error is located in this line:

 if ( x == -2.23f || x == (columns * 2.23f) ||y == -2.23f || y == (rows * 2.23f))

I am using this Unity tutorial as a guideline.

Here is the full code:

 using UnityEngine;
 using System.Collections;
 using System;
 using System.Collections.Generic;
 using Random = UnityEngine.Random;
 
 public class BoardManager : MonoBehaviour {
 
     [Serializable]
     public class Count
     {
         public int minimum;
         public int maximum;
 
         public Count (int min, int max)
         {
             minimum = min;
             maximum = max;
 
         }
     }
     //Number of Columns on board
     public int columns = 5;
     //Number off Rows on board
     public int rows = 4;
     //Number of inner walls to be made between (x, y)
     public Count wallCount = new Count(9,11); 
 
     public GameObject[] floorTiles;
     public GameObject[] innerWallTiles;
     public GameObject[] outerWallTiles; 
 
     private Transform boardHolder;
     private List<Vector3> gridPositions = new List<Vector3>();
 
 
 
     //2.23 is the size of each tile
     void InitialiseList()
     {
         //Empties previous grid positions
         gridPositions.Clear();
         //For each Column.....
         for (float x = 2.23f; x < (columns*2.23f) -2.23f; x+=2.23f) {
             //...Do each Row....
             for (float y = 2.23f; y < (rows*2.23f) -2.23f; y+=2.23f) {
                 //... To create a List of possible positions for each tile
                 gridPositions.Add(new Vector3(x, y, 0f)); 
 
             }
         }
 
     }
     //Creates "Canvas" with outer wall and background of floor
     void BoardSetUp() 
     {
         boardHolder = new GameObject("Board").transform;
         //Goes to columns +-2.23 is to create edge
         for (float x = -2.23f; x <(columns*2.23f) + 2.23f; x+=2.23f){
             //Goes to rows +-2.23 to create edge
             for (float y = -2.23f; y <( rows*2.23f) + 2.23f; y+=2.23f){
                 //Randomly chooses a Floor tile design (Allows more to be added later due to length not being specified)
                 GameObject toInstantiate = floorTiles[Random.Range(0, floorTiles.Length)];
                 //Checks whether it is the games border
                 if ( x == -2.23f || x == (columns * 2.23f) ||y == -2.23f || y == (rows * 2.23f))
                 {
                     //Picks a random outer wall tile to instantiate
                     toInstantiate = outerWallTiles[Random.Range(0, outerWallTiles.Length)]; 
                 }
                 //Creates tile at correct coordinates (x,y,0) with no rotation (quaternion) as a new gameobject
                 GameObject instance = Instantiate(toInstantiate, new Vector3(x, y, 0f), Quaternion.identity) as GameObject;
                 //Sets parent as board Holder for easy management
                 instance.transform.SetParent(boardHolder); 
             }
         }
     }
 
     Vector3 RandomPosition()
     {
         //Selects random positions
         int randomIndex = Random.Range(0, gridPositions.Count); 
         Vector3 randomPosition = gridPositions[randomIndex];
         //Removes the Position
         gridPositions.RemoveAt(randomIndex);
         //Returns the value random position
         return randomPosition; 
 
     }
 
     void LayoutObjectAtRandom (GameObject[] tileArray, int minimum, int maximum)
     {
         //Controls how many of an object spawn
         int objectCount = Random.Range(minimum, maximum + 1);
         //For the number in objectCount.....
         for (int i=0; i < objectCount; i++) 
         {
             Vector3 randomPosition = RandomPosition();
             //Picks a Tile
             GameObject tileChoice = tileArray[Random.Range(0, tileArray.Length)];
             //Creates The tile
 
             Instantiate(tileChoice, randomPosition, Quaternion.identity); 
         }
     }
     //Public so can be accessed outside of file by GameManager script
     public void SetupScene() 
     {
         BoardSetUp();
         InitialiseList();
         //Lays out the tiles
         LayoutObjectAtRandom(innerWallTiles, wallCount.minimum,wallCount.maximum); 
     }
 }

Thank you for helping me.