Apache not parsing PHP behind Nginx reverse proxy

I’m trying to build an Ubuntu 18.04 based, Apache PHP-FPM web server with multiple virtual hosts, behind Nginx as a reverse proxy. Everything works fine up to the point where I configure Nginx to be the reverse proxy. Now I have this:

• static HTML files are OK

• php files are downloaded instead of executed

• the worst thing is that when I try to fetch my info.php (which only has the basic HTML5 scaffold with title meta tag, to know which virtual host is served, and <?php phpinfo(); ?>) I’m being served with the different file, without a clue from where it was served.

When bypassing Nginx on port 8080 everything is back to normal and my PHP is working.

Here’s my /etc/nginx/sites-available/apache (my_server_ip is real IP):

server {
    listen 80;
    server_name foobar.net www.foobar.net test.io www.test.io;

    location / {
        proxy_pass http://my_server_ip:8080;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

I’ve lost two days so far, I found no similar issues on the web, and I’m desperate so any help would be greatly appreciated.

Cheers.