Nginx allow user agent specific directory - .htaccess

Question

I migrate apache to nginx.
In apache I put .htaccess inside folder, but nginx hasn't this.
I have folder /admin and it can only by accessed by User Agent: Administrator
I do:
location ~ /admin {
if ($http_user_agent !~* "Administrator") {
return 404;
}
try_files $uri =404;
}
And it works, but .php files isn't interpreted.
How can I do this?
Edit:
server {
listen 80;
server_name myserver.com;
root /usr/share/nginx/html;
location / {
}
location ~ /admin {
if ($http_user_agent !~* "Administrator") {
return 404;
}
try_files $uri =404;
}
location ~ \.php$ {
try_files $uri =404;
fastcgi_pass unix:/run/php-fpm/php-fpm.sock;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;
}
include /etc/nginx/default.d/*.conf;
}

Answer 1

There is problem with the specification about agent callback instead of "Administrator" it should be (Administrator) rest of the code seems to be ok. If you have added try_files $uri =404; additionally then remove it as it don't required. return 404 already defined.
Try this one
server {
listen 80;
server_name myserver.com;
root /usr/share/nginx/html;
location ~ \.php$ {
try_files $uri =404;
fastcgi_pass unix:/run/php-fpm/php-fpm.sock;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;
if (!-e $request_filename) {
rewrite ^.*$ /index.php last;
}
}
location ~ /admin {
if ($http_user_agent !~* "Administrator") {
return 404;
}
try_files $uri =404;
}
include /etc/nginx/default.d/*.conf;
}
restart nginx service before test!