Problem back again. I removed the page completely and re-created it as a public page. everything worked fine.
Now I made it password protected again and the same problem occurs. It just requests the password endlessly.
I’m sure it has something to do with changing the website URL but I don’t know what.
my .htaccess file is empty (excpet for the start/end WordPress tags). if that’s any clue.
Is there somthing I’m missing?