Plesk Nginx Browser caching on port 3100?

Hi
I want to enable browser caching for a single .JS file served thru port 3100.

For all normal web files I use this in my Plesk Apache / nginx custom field:

location ~* \.(js|css|png|jpg|jpeg|gif|ico)$ {
expires 30d;
add_header Cache-Control "public";
try_files $uri @fallback;
etag on;
if_modified_since before;
access_log off;
}

This works for my port 80 files.
But I have a single file served thru port 3100:...

Plesk Nginx Browser caching on port 3100?