If the problem is that Visual Studio updates the two settings in the applicationhost.config when opening the solution, you can solve it by selecting the Project in the Solution Explorer, view the Properties pane (available when you're not in debug mode) and set to Enabled the two items Anonymous Authentication and Windows Authentication.
By the way, in my case the parameter generating the 401.2 error was just Anonymous Authentication, you might want to try to leave the default one for Windows Authentication.
(PS, your post solved the problem for the 401.2 and really saved my day so many thanks for it!)