We have a single site collection setup within a web application. The site collection has one top-level site, and the setup has one content database. The application is using Forms authentication for its customers, along with Windows Authentication for its employees. For customers, the URL should be different from the URL the employees login to. (i.e. employee.userportal.com & userportal.com).
Currently we have a custom login screen that allows FBA users to enter their username or password. We also have an "Employee Login" link pointing towards the windows auth login prompt for employees. However, the client does not want customers to see the "Employee Login" link.
How can I setup a seperate URL for the login page/authentication, but keep the simple, single web-application/site-collection approach?
SharePoint 2013 On-premise.