The WAYF selection page shows all Identity Providers that have allowed access to your service. (example for desktop/laptop and for mobile format; for a live example go to SURFconext Teams and click on [Log in]).
The SURFconnect WAYF page is automatically used when you connect to SURFconext using the basic Identity Provider metadata. This way, you configure SURFconext to be your service's only Identity Provider..
Show all Identity Providers
Standard if an IdP has not (yet) proved access to your service, he is not shown on the WAYF page and users cannot login with that IdP.
There is however an option to show all Identity Providers. IdPs that have not yet been coupled are overlayed with a 'request access' link. When a user clicks on such an IdP, he can request access to the service. SURFconext will forward the request to your organization.