I installed October cms on nginx server, looks like everything is working except I cannot access /backend 404 not found.

My nginx config

server {
    listen 80;
    listen [::]:80;

    root /var/www/417rct;

    index index.php index.html index.htm index.nginx-debian.html;

    server_name 417rct.org;

    location / {
        # First attempt to serve request as file, then
        # as directory, then fall back to displaying a 404.
        try_files $uri /index.php$is_args$args;
    }

    rewrite ^themes/.*/(layouts|pages|partials)/.*.htm /index.php break;
    rewrite ^bootstrap/.* /index.php break;
    rewrite ^config/.* /index.php break;
    rewrite ^vendor/.* /index.php break;
    rewrite ^storage/cms/.* /index.php break;
    rewrite ^storage/logs/.* /index.php break;
    rewrite ^storage/framework/.* /index.php break;
    rewrite ^storage/temp/protected/.* /index.php break;
    rewrite ^storage/app/uploads/protected/.* /index.php break;

    location ~ \.php$ {
        include snippets/fastcgi-php.conf;
        fastcgi_pass unix:/run/php/php7.0-fpm.sock;
    }

    location ~ /\.ht {
        deny all;
    }
}