Nginx reverse proxy causing infinite loop

问题

I have the following in my Nginx site config file:

server {
    listen 80 default_server;
    listen [::]:80 default_server ipv6only=on;

    root /usr/share/nginx/html;
    index index.php index.html index.htm;

    server_name example.com;

    location / {
        try_files $uri $uri/ /index.php?q=$uri&$args;
    }

    error_page 404 /404.html;
    error_page 500 502 503 504 /50x.html;
    location = /50x.html {
        root /usr/share/nginx/html;
    }

    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php5-fpm.sock;
        fastcgi_index index.php;
        include fastcgi_params;
    }
}


server {
    listen 80;
    server_name example2.com;

    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $remote_addr;
        proxy_set_header Host $host;
        proxy_pass http://localhost/page-1/;
    }
}

The issue only seems to occur when I add the proxy_set_header Host $host; line. It appears that the $host variable creates a redirect loop and the GET request from the error server logs goes something like this ...page-1/page-1/page-1/page-1... with the server responding with an internal error 500.

I'd be really grateful if anyone could tell me what I'm doing wrong. Many thanks in advance!