HP iLO is an out-of-band server control interface which is used to control the server even when the OS that is installed on it is offline, or completely damages/uninstalled. For this to implement, it has a separate IP address, and, if installed properly, a separate LAN port (shared mode, when it's connected through the OS interfaces is available, but it's a source of many problems). This also means that it has it's own network controller and it's own IP address, so saying 80 and 443 are already taken by nginx you cannot be more wrong, because either your iLO is misconfigured and thus not working, either iLO and your OS have completely different IP addresses and probably VLANs.