For some people Facebook is the internet and for others it is Outlook. Somehow a twiddler at MS has decided that a file on a web server at some wanky location is the internet and that's the final answer.
"I cn haz a file" is fine lovely internets! No it bloody well isn't. You should be constructing a response to a challenge from the other end, not a response to a simple GET like it's 1999.
I run quite a few systems/sites that have multiple internet connections - deciding whether the internet is available is quite a nuanced thing and that Windows internet detector is bloody stupid, naive and a fucking hindrance.
Define "internet" and then have a crack at defining "internet accessibility". Those things are quite specific to individuals. orgs and so on. Connectivity is way too complicated for a simple, naive check.