MySql server connecting/working in the editor but not in the build

Below there would be an example of one of the scripts accesing the database (it’s hosted on GearHost using SSMS)
It’s the first time I’m useing a database so I’m not really sure what I am missing. Couldn’t find any helpful solution online. The only thing I found suggested to include the Il18N.West.dll which just gives me another assembly error.

Help is greatly appreciated.

The script (The InsertPlayerName is the importnant part):

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using System.Data.Sql;
using System.Data.SqlClient;
using TMPro;

public class End : MonoBehaviour
{
    [SerializeField] private TextAsset dbPath;
    public RaycastHit hit;
    private string playerName;
    private int currentID;
    [SerializeField] private Canvas m_PromptCanvas;
    [SerializeField] private Canvas m_UsernameCanvas;
    [SerializeField] private TMP_InputField m_UsernameInput;
    [SerializeField] private Canvas m_NoInternetCanvas;

    void Start()
    {
        m_PromptCanvas.enabled = false;
        m_UsernameCanvas.enabled = false;
        m_NoInternetCanvas.enabled = false;
    }

    void Update()
    {

        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        if (m_NoInternetCanvas.enabled)
        {
            if (Input.GetButton("Cancel"))
            {
                m_NoInternetCanvas.enabled = false;
            }
        }
        else if (m_UsernameCanvas.enabled)
        {
            if (Input.GetButton("Cancel"))
            {
                m_UsernameCanvas.enabled = false;
            }

            if (Input.GetButton("Enter") && !string.IsNullOrWhiteSpace(m_UsernameInput.text))
            {
                PlayerPrefs.SetString("username", m_UsernameInput.text);
                PlayerPrefs.Save();
                m_UsernameCanvas.enabled = false;
                m_PromptCanvas.enabled = false;
            }
        }
        else if (m_PromptCanvas.enabled)
        {

        }
        else if (Physics.Raycast(ray, out hit, Mathf.Infinity, Physics.DefaultRaycastLayers, QueryTriggerInteraction.UseGlobal) && hit.collider.gameObject.tag == "Button")
        {
            hit.collider.gameObject.GetComponent<ButtonSwing>().changeSize = true;
            hit.collider.gameObject.GetComponent<ButtonSwing>().timeSinceHit = 0;
            if (Input.GetKeyDown(KeyCode.Mouse0))
            {

                if (hit.collider.gameObject.name == "Main Button")
                {
                    SceneManager.LoadScene("Main Menu", LoadSceneMode.Single);
                }
                else if (hit.collider.gameObject.name == "Restart Button")
                {
                    SceneManager.LoadScene("Test Main", LoadSceneMode.Single);
                }
                else if (hit.collider.gameObject.name == "Leaderboard Button")
                {
                    if (!string.IsNullOrWhiteSpace(PlayerPrefs.GetString("username")))
                    {
                        playerName = PlayerPrefs.GetString("username");
                        m_PromptCanvas.enabled = false;
                        InsertPlayerName();
                        InsertScore();
                        SceneManager.LoadScene("Leaderboard", LoadSceneMode.Single);
                    }
                    else
                        m_PromptCanvas.enabled = true;
                }
            }
        }
    }


    public void InsertPlayerName()
    {
        string content = dbPath.text;

        using (SqlConnection con = new SqlConnection(content))
        {
            string sqlcmd = "IF NOT EXISTS(SELECT player FROM dbo.Players WHERE player = '" + playerName + "') BEGIN INSERT INTO dbo.Players(player) VALUES('" + playerName + "') END";
            using (SqlCommand cmd = new SqlCommand(sqlcmd, con))
            {
                cmd.CommandType = System.Data.CommandType.Text;

                try
                {
                    con.Open();
                    cmd.ExecuteNonQuery();

                }
                catch (SqlException)
                {
                    m_NoInternetCanvas.enabled = true;
                }
            }
            con.Close();
        }
    }

The screenshot of errors in the devolpment build:

By the way - I recently also tried copying the System.Data.dll into my project folder. Same error in the build