how can I change the website (my domain, where the AMP login appears)? For legal reasons I have to add an imprint/data protection on this page (Germany).
Another alternative would probably be if I change the port of the login page so that the page is not even displayed when I enter my domain. To do this I would need to know where I can change the port (can i choose one i want?) and whether there will be any problems afterwards.
If you go to Configuration > Branding > Brand Links - one of the options is “Splash screen frame URL” - this lets you specify a URL to a page and it will appear on the login screen. So you can use this for things like disclosures or other notifications that you need to be publicly visible before logging in.