Oneboxes not created for Lupa.cz on our site, work elsewhere

[zoul (Tomáš Znamenáček)]

Hello, I am trying to create link previews for this site on our Discourse instance:

Lukáš Němčík (COOP): Letos budeme mít až stovku automatizovaných prodejen -...

As you can (hopefully) see, the onebox works here, but on our instance it does not:

Oneboxes for other sites work fine. What could be the problem, apart from the target website blocking us for some reason? How can I troubleshoot the problem?

[Lilly]

maybe have a look at your forum’s various onebox settings go to admin-settings and type “onebox” in the settings filter box at the top. Have a look at this topic:

Onebox configuration and troubleshooting

While users can create rich link previews in their posts using oneboxes (See: Create rich link previews with Onebox), there are some controls available to site administrators, and sometimes when links do not preview as expected, it can be helpful to do a bit of troubleshooting to understand why. Admin configuration Site administrators can control many of the onebox settings in the site setting section. To see available settings search for onebox. [onebox-site-settings] Notable settings are: …

[pfaffman (Jay Pfaffman)]

@zoul

the target website blocking us for some reason

That’s my guess. If you have lots of links to them you could be rate limited. If they look right in preview but not when the post is rendered, this is the issue.

[zoul (Tomáš Znamenáček)]

I’ve asked them about it and they are not blocking us. The link is not oneboxed in preview nor when the post is published. Is there somewhere I can peek at to see the particular error?