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It can't be Cloudflare, there is no block of whole countries possible.
It must be a plugin, which blocks special countries, because also the normal server softwares have no possibility to block whole countries from playing. So it would be very helpful to give us the username of the person who hosts the server (optional with pn for privacy) so we can have a closer look on it.
It was one of the plugins he had on the server. He removed them all at once and I was able to connect to the server fine. I don't know what plug-in is causing this.