Setting the Service Portal to use External login by defaultDescriptionSSO is already Enabled and it's working properly (the user gets automatically logged in to the instance). But when they are accessing a Portal link( https://<instance-name>.service-now.com/sp ), the user needs to log in using External login, instead of being sent to the internal portal login page.ResolutionThis can be achieved by customizing the login widget (after cloning it) as there is no separate "external login" widget. An example of how to do this is explained in a Community blog article:How to Set Service Portal Login to default to External Login - Multi SSO