Hi Friends!
Sometimes if you want to get all post from main site into sub site. So please refer my below code.
switch_to_blog( $blog_id ); // put code for all post here. restore_current_blog();
switch_to_blog($blog_id);
= This is switch to the site in network as per the ID.
You have added the main site id. So it will switch to the main site.
restore_current_blog();
= will restore the current blog.
I hope this article will help you 🙂