Just received a warning email from the service provider(Hetzner).
We have indications that there was an attack from your server.
Please take all necessary measures to avoid this in the future and to solve the issue.
We also request that you send a short response to us. This response should contain information about how this could have happened and what you intend to do about it.
In the event that the following steps are not completed successfully, your server can be blocked at any time after the 2021-04-XX XX:XX:XX +0100.
Discourse cannot easily apply Cloudflare as a defense…
Can’t hide the real IP address of my server…
Often under attack.