How do I embed oEmbed / OpenGraph tags in my website?

I am trying to embed OpenGraph tags in my website, so that when I post a link to my website on this forum, it would look nice and informative. I've taken a look at and added the following lines to my index.html file, <head> section (changed real domain name to here):

  <meta property="og:title" content="My Title" />
  <meta property="og:type" content="website" />
  <meta property="og:url" content="" />
  <meta property="og:image" content="" />
  <meta property="og:image:width" content="48" />
  <meta property="og:image:height" content="48" />
  <meta property="og:description" content="My description" />

However when I post a link to my website on this forum, I see just the URL and the error message

Sorry, we were unable to generate a preview for this web page, because the following oEmbed / OpenGraph tags could not be found: description, image

Am I missing something?

Could it be a caching issue (the forum fetches older version of my webpage cached somewhere)?

i had a similar problem a while back that ended up being because the server was rejecting the crawl request from Discourse, because the Discourse script does not send an Accept-Language header. could your server be requiring Accept-Language in order to fulfill a request?

Hmm... Cannot say for sure. My server is (auto)configured by a web hosting company, not me. I think I'll just not use the tags - not a big deal.