ORA-24247: network access denied by access control list (ACL)

begin
   dbms_network_acl_admin.append_host_ace(
     host => 'renenyffenegger.ch',
     ace  =>  xs$ace_type(
        privilege_list => xs$name_list('connect', 'resolve'),
        principal_name =>'rene',
        principal_type => xs_acl.ptype_db
     )
   );
end;
/