LDAP SSO does not authenticate user on homepage

Question

I have configured ldap sso and it is working so far for all Url paths except for the homepage.

I get authenticated on /user/login/sso and I get authenticated on /whatsoever but I don't get authenticated on / The settings for Automated SSO is checked and my settings for Apache look like this:

 <Location />
            AuthType Kerberos
            KrbAuthRealms xyz
            KrbServiceName HTTP/xyz
            Krb5Keytab /usr/local/apache2/conf/conf.d/drdc.keytab
            KrbMethodNegotiate on
            KrbMethodK5Passwd off
            KrbSaveCredentials on
            require valid-user
    </Location>

I did check the default excluded paths in the ldap sso module, but couldn't find the path / there.
I have tried to redirect every not authenticated user to /user/login/sso but somehow this results in "to many redirects" (I want to keep /user/login/ free for loggin in as admin user without kerberos)

if ($event->getRequest()->getRequestUri() != '/user/login' && $this->currentUser->isAnonymous()) {
  if (preg_match('/\/comment\-([\d]+)/', $current_path)) {
    $destination = str_replace('/comment-', '#comment-', $current_path);
    user_cookie_save(['destination' => $destination]);
  }
  $url = '/user/login/sso';
  $response = new RedirectResponse($url);
  $event->setResponse($response);
  return;

Any idea?

Answer 1

This works now after unchecking this setting in the SSO-Module konfig: