That's can be affected in /usr/local/nginx/conf/nginx.conf. Considering the following change ('-' means to remove line, '+' to add a new one):
location /download_f/ {
<...>
+ max_ranges 0;
}
location /download_r/ {
<...>
+ max_ranges 0;
}
Note: please don't forget to re-read config by executing 'killall -1 nginx'.