> For the complete documentation index, see [llms.txt](https://documentation.rcore.cz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://documentation.rcore.cz/faq/cannot-verify-license.md).

# Cannot verify license

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**There are several reasons that can cause this problem. Make sure you check all of them.**
{% endhint %}

1. Make sure your **firewall is not blocking** ports 80/443.
2. Check the version of your server. *Old server versions can cause timeout requests.*
3. AntiDDOS may be blocking our server.

For the point 3. You will need to allow these IPs mentioned below

1. 193.70.80.3
2. 2001:41d0:303:203::