For a single one of the 25 sites I maintain, clicking Go to the site WP admin on the dashboard doesn’t redirect to the dashboard but to the login screen. Administrator user name and Unique security ID are 100% correct, site connected.
The only thing I can think of that is different to all other sites I maintain is that it is redirected to a subdirectory (sub.directory, the name contains a dot) install via index.php:
require( dirname( FILE ) . ‘/sub.directory/wp-blog-header.php’ );
Dashboard 184.108.40.206, child 4.0.7. Deactivating other plugins to no avail.