crobincouk

Solution: Using Custom HTML for Twitter Embeds in WordPress

Instead of using the default Twitter embed block in WordPress, you can use custom HTML with the blockquote version of the tweet. This option won’t affect older posts.

1. Find the Tweet you want to embed and click on the ... icon (More).
2. Choose “Embed Tweet” and copy the HTML code provided by Twitter.
3. In your WordPress editor, instead of choosing the Twitter block, choose the Custom HTML block.
4. Paste the copied Twitter HTML into the block.

Did you check my video ? https://www.youtube.com/watch?v=M-5gqWiApbk

Any Tweet will not work.

My server is located also at Hetzner (Finland).

Nops, I did that already, even a fresh installed WordPress Website will give the same error. I have seen on another forum many more people having the same issue.

https://twittercommunity.com/t/wordpress-fails-to-embed-tweets/194433/18