WP REST API endpoints for subdomain(s)

Hi,
I’ve a multisite installation where my main domain is http://mydomain.com/wordpress

A second domain is located at http://mydomain.com/wordpress/second so it’s a subdomain.

I’ve installed WP REST API plugin version 2.0-beta13.1 and network-enabled it

If I call the WP REST API on my main domain with:
http://mydomain.com/wordpress/wp-json/wp/v2/post
I get what I need

If I call the WP REST API on my subdomain with:
http://mydomain.com/wordpress/second/wp-json/wp/v2/post
I get this error:
{“code”:”rest_no_route”,”message”:”Nessun percorso fornisce una corrispondenza tra l’URL e le modalit\u00e0 di richiesta”,”data”:{“status”:404}}

How can I use WP REST API on a subdomain?
There are special endpoints for it?

Thanks.
Best.