Browsing to IP addresses directly does not work because of virtual hosting: https://en.wikipedia.org/wiki/Virtual_hosting Virtual hosting requires the “Host” header. You can see that this request returns 404: $ curl http://91.189.88.152/ubuntu/ but if I send the header it works fine: $ curl -H “Host: …

Ubuntu VPS Hosting via [Bug 1745129] Re: DNS for security.ubuntu.com and archive.ubuntu.com resolves to IP address ….