If your website does not use pretty printing wp-json will not be the correct url. You will know if your site uses pretty printing because the links will be https://www.example.com/?p=3 instead of https://www.example.com/my-article-slug.
If wwww.example.com/wp-json/ is not returning JSON data try https://www.example.com/index.php?rest_route=/. If you are at a real loss then get the output of `get_rest_url to find the REST url
