It's possible that your site's IP was used previously for some other sites and it was indexed as http://IP/... now google will retry to fetch the urls for a time.
Maybe you have someone's domain resolving to your IP. Seems to me that nginx is resolving the IP to the default site in the config.
Maybe you have someone's domain resolving to your IP. Seems to me that nginx is resolving the IP to the default site in the config.