On a intranet website, there is a public page in which there is a form (this page can be reached by anonym user)
For this form, i choose a public page as success page.
But when i submit data from form, in am not redirected to success page but on login page.

The problem is the same is no success page is choosen. It is necessary to be authenticated to see confirmation message (even if the page in which there is the form is public).