Forces HTTP/1.1 for outgoing connections in WordPress instead of HTTP 1.0

use-http11-in-wordpress.php

<?php
/**
 * Plugin Name: Use HTTP/1.1 in WordPress
 * Plugin URI: https://www.saotn.org/
 * Donate URI: https://www.paypal.me/jreilink
 * Description: MU Plugin. Forces HTTP/1.1 for outgoing connections in WordPress instead of HTTP 1.0
 * Network: True
 * Version: 1.0
 * Author: Jan Reilink
 * Author URI: https://www.saotn.org
 * License: GPLv2
 */

// see https://www.itfaq.nl/forceer-http-1-1-voor-uitgaande-verbindingen-in-wordpress/ for a Dutch article
// 
add_filter('http_request_args', 'saotn_http_request_args', 10, 3);
function saotn_http_request_args($r) {
	$r['httpversion'] = 1.1;
	return $r;
}

add_action('http_api_curl', 'saotn_http_api_curl', 10, 3);
function saotn_http_api_curl($handle) {
	curl_setopt( $handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1  );
}

add_filter( 'plugin_row_meta', 'saotn_http11_plugin_row_meta', 10, 2 );
function saotn_http11_plugin_row_meta( $links, $file ) {
	if ( !preg_match('/use-http11-in-wordpress.php$/', $file ) ) {
		return $links;
	}
	$links[] = sprintf(
		'<a target="_blank" href="https://paypal.me/jreilink" title="Donate to Jan Reilink / Sysadmins of the North">%s</a>',
		__( 'Donate' )
	);
	return $links;
}