[falko]

Please open /home/admispconfig/ispconfig/lib/config.inc.php. You should find something like this:

if(isset($_SERVER['SERVER_NAME']) && isset($_SERVER['SERVER_PORT'])){
  $go_info["server"]["server_url"] = 'https://'.$_SERVER['SERVER_NAME'].':'.$_SERVER['SERVER_PORT'];
} else {
  $go_info["server"]["server_url"] = "https://blabla:81";
}

Replace it with this:

if(isset($_SERVER['HTTP_HOST']) && isset($_SERVER['SERVER_PORT'])){
  $go_info["server"]["server_url"] = 'https://'.$_SERVER['HTTP_HOST'].':'.$_SERVER['SERVER_PORT'];
} else {
  $go_info["server"]["server_url"] = "https://blabla:81";
}