Membership Lock down will lock all post content including attached images, video, docs, and everything else, everywhere.
All who try to visit the site will be redirected to the login page.
The administrator can enable and disable the lock down as needed. 
Only registered website users will be able to access,
If a user is not logged in we will redirect them to the login page.

Membership Lock

Membership Lock down lets you easily lock all post content including attached images, video, docs, and everything else.

David Sader

Adds three more levels of privacy(visibility) to the Settings–>Reading page.
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Site visible to any logged in community member – “Network Users Only”.
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Site visible only to registered users of blog – “Site Members Only”.
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Site visible only to administrators – “Site Admins Only”.
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</ol>
<a href="https://codex.wordpress.org/Create_A_Network" rel="nofollow ugc">Multisite</a> Network Admin can set an override on site privacy at “Network Visibility Selector” on Network Settings page
Multisite Network Admin can set privacy options at Network-Sites-Edit under “Settings Tab” as well.
Network Admin receives an email when blog privacy changes.
RSS feeds require authentication.
robots.txt updates accordingly.
Ping sites filters correctly.
Privacy status reflected in Dashboard “Right Now” box.
Uses WP3+ functions auth_redirect(), network_home_url(), and home_url() for SSL login redirects.
Login message has link to sign-up page of a “Network Users Only” blog or a link the blog admin email if user is logged in but not a member of a “Members Only” blog.
Localization ready.

More Privacy Options

Hi. 
Thanks for the great plugin. 
It works out-of-the-box in WP 4.9.8

Kudos!!!

Simple and elegant

Adds three more levels of privacy(visibility) to the Settings-->Reading page.

Membership Lock vs More Privacy Options