See if this removes warning

etc/nginx/conf.d/default.conf

@@ -4,7 +4,7 @@ server {
 
     root /var/www;
     index index.html;
-    server_name _;
+#    server_name _;
 
     access_log /var/log/nginx/access.log;
     error_log /var/log/nginx/error.log;