Create your own cache server

Base : https://blog.lael.be/post/7605
Blog post : https://marshallku.com/web/tips/캐시-서버-구축하기

Features

• Cache Images, Videos (png, jpg, jpeg, gif, webp, mp4, webm, svg)
• Create WebP Images, and cache them

Just place .webp after the image's url to convert them in webp files.
eg. https://example.com/src/images/tmp.png.webp

How to Install

You might use PHP lower than 8.0

Replace example.com to your domain.
You should update both nginx.conf and index.php.

Create Nginx configuration file

Create your own nginx configuration file with nginx.conf file in /etc/nginx/sites-available

sudo ln -s /etc/nginx/sites-available/example.com /etc/nginx/sites-enabled/

and link that file in /etc/nginx/sites-available

Add files in web root folder

Place every files in www folder in /home/cdn/www

Restart Nginx, PHP-fpm

sudo systemctl nginx restart
sudo systemctl php8.0-fpm restart

Replace every images' link

function imgToPicture($content)
{
    preg_match_all('/<img(.+?)(src=\"(.+?)\")(.+?)(srcset="(.+?)")? ?\/?>/', $content, $matches);
    $i = 0;
    foreach ($matches[0] as &$image) {
        // Replace domain to cache server domain
        // Replaces https://example.com/img.png to https://img.example.com/img.png
        $src = str_replace('//example', '//img.example', $matches[3][$i]);
        $srcset = $matches[6][$i] ?? '';
        $srcset = $srcset != '' ? preg_replace('/\/\/example/', '//img.example', $srcset) : '';

        $webpSrcset = $srcset != '' ? preg_replace('/\.(png|jpe?g)/', '.$1.webp', $srcset) : '';

        $tmp = "<picture><source type=\"image/webp\" srcset=\"{$src}.webp 1x,{$webpSrcset}\"></source><source srcset=\"{$src} 1x,{$srcset}\"></source><img{$matches[1][$i]}src=\"{$src}\"{$matches[4][$i]}srcset=\"{$srcset}\"></picture>";

        $content = str_replace($image, $tmp, $content);
        $i++;
    }
    return $content;
}

add_filter('the_content', 'imgToPicture');

Simple example with the code that I used for my wordpress theme.