Facebook api – Getting embbeded Facebook comments from site

I would like to retrieve the embedded Facebook comments from the page web:

(http://www.example.com/sub_page_wFBcomments)

What I know

I can use the Facebook graph API for retrieving facebook comments directly from facebook.com.
The same is not true when the comments are embedded in the web site of the facebook page’s owner.

What I’ve tried

When using the graph API like this:

https://graph.facebook.com/v2.7/[apikey]/?key=value&access_token=[MyToken]

    {
       "link": "http://www.example.con/",
       "name": "Example.com",
       "namespace": "examplecom",
       "id": "[apikey]"
    }

And when naively adapting to the comments:
[link] https://graph.facebook.com/v2.7/[apikey]/posts/?key=value&access_token=[MyToken]

It does not work, I get:

 "message": "(#100) Tried accessing nonexisting field (posts) on node type (Application)",
 "type": "OAuthException",

The facebook page has no comments/posts to show.
(But when doing [apikey] = walmart, it downloads the comments of the facebook page)
So I deduced something is missing: how the api would know where to look for the comments ?

How far I got:

Stackoverflow suggested to use something like
/comments/?ids= "link of page"
which does not work:

https://graph.facebook.com/v2.7/[apikey] /comments/?ids=http://www.example.com/sub_page_wFBcomments&access_token=[MyToken]

"message": "(#100) Tried accessing nonexisting field (comments) on node type (Application)",

remark
When removing “/coments” from the previous url I recover the body in a .json, but not the comments.

Question:

Is it possible to make the api to look for the comments in ?
http://www.example.com/sub_page_wFBcomments
(and not from www.facebook.com/exemplecom)

Thanks for your help.

Edit

Following the @CBroe remark, I’ve tried the FAQ on the example

http://www.oneminuteinfo.com/2015/06/how-to-use-fb-api-to-get-fan-page-posts.html

    https://graph.facebook.com/v2.6/?fields=og_object{comments}&id=http://www.url.com&access_token=[MyToken]

    {
      "og_object": {
         "id": "1305277432850801"
      },
       "id": "http://www.oneminuteinfo.com/2015/06/how-to-use-fb-api-to-get-fan-page-posts.html"
    }

Comments missing 🙁

Edit 2

Thanks for the answer @TomSanders. I tried your suggestion, and it is still not working, the id I retrieved using the url is not the one that gives the comments, I explain myself:

From

https://graph.facebook.com/v2.3/[myUrl]/comments?limit=100&access_token=[myToken]

I get:

{
   "og_object": {
      "id": "813606582071724",
      "description": "the description",
      "title": "the title",
      "type": "website",
      "updated_time": "2016-10-15T16:57:59+0000"
   },
   "share": {
      "comment_count": 0,
      "share_count": 0
   },
   "id": "myUrl"
}

Remark 1 when changing the url address from http to https the “comment_count” becomes = 141.

Remark 2 using the id this request got in the next step I retrieve an empty data: {“data”:[]}.

Remark 3 (!!) when right-clicking on the facebook plugin of the website I carn get the facebook id by looking for targetid = 1065663070140433. Then, when I plug it in the api I get (some of the) comments!

What am I doing wrong here? I need lights.