Redirect wp-signup.php When Registration Is Closed
Sends visitors who land on wp-signup.php to a page you choose (or the homepage) when network registration is turned off, instead of showing a bare "Registration has been disabled" screen.
Snippet Library
Multisite snippets for WordPress
Snippets for WordPress Multisite networks: network-wide settings, new site defaults, super admin tools and cross-site tweaks. For network administrators who manage many sites from one install.
Return to the Main Site After Logging Out
Sends users to the network's main homepage when they log out from any site, giving the whole network one consistent exit point.