Multisite wp-signup.php redirect issue

I’m setting up a git repository to manage an existing WordPress multisite (using subdomains), and also a dev and staging server.

The url to access the dev server is https://dev.www.example.com. The wp-content folder is outside of the WordPress folder such that I can update the core WordPress files in the repository, and wp-config.php is in the root directory outside of the WordPress folder.

The constants in wp-config.php look like this:

define( ‘WP_HOME’, ‘https://dev.www.example.com’ );
define( ‘WP_SITEURL’, ‘https://dev.www.example.com’ );
define( ‘MULTISITE’, true );
define( ‘SUBDOMAIN_INSTALL’, true );
define( ‘DOMAIN_CURRENT_SITE’, ‘dev.www.example.com’ );
define( ‘PATH_CURRENT_SITE’, ‘/’ );
define( ‘SITE_ID_CURRENT_SITE’, 1 );
define(‘BLOG_ID_CURRENT_SITE’, 1);
define( ‘ADMIN_COOKIE_PATH’, ‘/’ );
define( ‘COOKIE_DOMAIN’, ‘dev.www.example.com’ );
define( ‘COOKIEPATH’, ” );
define( ‘NOBLOGREDIRECT’, ‘https://dev.www.example.com’ );

In the database, the siteurl and the home url (in wp_options) are as above, and also the blog_id domain (in wp_blogs) is correct as per above.

However when accessing wp-admin, I get redirected to https://www.example.com/wp-signup.php?new=dev (i.e. to the production site instead of the wp-admin for the dev site) . I can’t find a way to solve this. Any suggestions?