nginx wrong with systemd

[supersnd]

default.conf
location / {
        #root   /usr/share/nginx/html;
        root /sdd/;
        #index  index.html index.htm;
        autoindex on;
[root at centos /]# /usr/sbin/nginx -c /etc/nginx/nginx.conf
 I can read the files
[root at centos /]systemd start nginx
403 Forbidden
nginx/1.9.15
 I add User=root to nginx.serivce
the question still have

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,266640,266640#msg-266640