Crystal reports - database logon failed only on production machine

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C#

IIS

CrystalReports

Hello,

I am developing a web app that has reports created on VS 2019 and run fine from developer mode, but when I publish the website I get "Database logon failed" Error. Database server is on different server that development and production machine.
The error is throwing in line

cryRpt.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat)

Note that I have the same version of crystal reports installed to developer and production machine and aspnet_client folder is on wwwroot.

Development machine: Windows 10, Visual Studio 2019, Crystal Reports v4.0.30319
Production machine: Windows Server 2012 R2, Crystal Reports v4.0.30319

What could be causing this? Thank you in advance.

This is my code:

public void sendEmail(int id)
    {
        ReportDocument cryRpt = new ReportDocument();
        TableLogOnInfos crtableLogoninfos = new TableLogOnInfos();
        TableLogOnInfo crtableLogoninfo = new TableLogOnInfo();
        ConnectionInfo crConnectionInfo = new ConnectionInfo();
        Tables CrTables;

        cryRpt.Load(@"C:\temp\rep1.rpt");
        
        crConnectionInfo.ServerName = "server";
        crConnectionInfo.DatabaseName = "db";
        crConnectionInfo.UserID = "username";
        crConnectionInfo.Password = "pass";

        CrTables = cryRpt.Database.Tables;
        foreach (CrystalDecisions.CrystalReports.Engine.Table CrTable in CrTables)
                {
                    crtableLogoninfo = CrTable.LogOnInfo;
                    crtableLogoninfo.ConnectionInfo = crConnectionInfo;
                    CrTable.ApplyLogOnInfo(crtableLogoninfo);
                }

        cryRpt.SetParameterValue("@ID", id);

        emailCreator(from, to, subject, body, "Attachment.pdf", cryRpt.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat));
    }

What I have tried:

1.I enabled 32-bit Application on Application Pool.
2.I changed Identity to Administrator (Application Pool --> Advance Settings) and back to ApplicationPoolIdentity, since it didn't work.
3.I try connecting from IIS Server to database server using the reports credentials to check if I have access and there is access.