Large excel file is not generating, getting error: ERR_INVALID_RESPONSE - php

Question

Using PHPExcel library in Codeigniter.
Small excel file of about 20k row lines are generating perfectly, while in the case of large (like 43k row lines) file it gets:
This site can’t be reached
The webpage at
https://exmple.com/
might be temporarily down or it may have moved permanently to a new web address.
ERR_INVALID_RESPONSE
I've tried-
ini_set('max_input_vars', 19999);
set_time_limit ( 6000 );
ini_set('max_execution_time', 6000);
memory_get_usage(true);
but didn't get result.
Codeigniter Version: 3.1.11
PHP Version: 7.4
Part of code if needed (its not exact code):
public function test(){
$this->load->library('Excel');
ob_start();
// Create new PHPExcel object
$objPHPExcel = new PHPExcel();
$exlHeading = array(
'font' => array(
'bold' => true,
'size' => 12,
'name' => 'Verdana')
);
// Set document properties
$objPHPExcel->getProperties()->setCreator("BigDream India")
->setLastModifiedBy("TEST")
->setTitle("REPORT")
->setSubject("ATTENDANCE REPORT")
->setDescription("Attendance Monthly Report")
->setKeywords("ATT_REPORT")
->setCategory("Excel Sheet");
for($i=0; $i<=40000; $i++){
$objPHPExcel->setActiveSheetIndex(0)->setCellValue('A'.$i, 'Test content is here.');
$objPHPExcel->setActiveSheetIndex(0)->mergeCells("A$i:I$i");
$objPHPExcel->getActiveSheet()->getStyle("A$i:I$i")->applyFromArray($exlHeading);
}
$objPHPExcel->getActiveSheet()->setTitle('Attendance Monthly Report');
$objPHPExcel->setActiveSheetIndex(0);
ob_end_clean();
$filename = 'MyOfficeGuardian-Monthly_Report.xls';
header('Content-type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="' . $filename . '"');
header('Cache-Control: max-age=0');
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel5');
$objWriter->save('php://output');
}

Answer 1

Issue resolved by just updating upload_max_filesize value from 2mb to 20mb in php.ini file.