SSL-ForFree und kostenlose SSL Zertifikat

Unter diesem URL sollte man SSL Zertifikat bekommen können:

https://www.sslforfree.com/create?domains=example.com

Aber es funktioniert nicht, wie es sein sollte. Man bekommt ähnliche Fehlermeldung wie hier:

Domain "example.com" challenge3 failed. Response from "https://acme-v01.api.letsencrypt.org/acme/challenge/JCDhu0z8XPTOBxbe32RNdsw0PdNmxoMzsUsiIPRXOz9s/2547708628" was: { "type": "http-01", "status": "invalid", "error": { "type": "urn:acme:error:unauthorized", "detail": "Invalid response from http://example.com/.well-known/acme-challenge/4LnkxboZi7x29FEk8yIZez92g5tDMbipDLRFPNulpJIQ: \"\u003c!doctype html\u003e\n\u003chtml\u003e\n\u003chead\u003e\n \u003ctitle\u003eExample Domain\u003c/title\u003e\n\n \u003cmeta charset=\"utf-8\" /\u003e\n \u003cmeta http-equiv=\"Content-type\"", "status": 403 }, "uri": "https://acme-v01.api.letsencrypt.org/acme/challenge/JCDhu0z8XPTOBxbe3RNdsw0PdNmxoMzsUsiIPRXOz9s/2547708628", "token": "4LnkxboZi7x29FEk8yIZez55g5tDMbipDLRFPNulpJIQ", "keyAuthorization": "4LnkxboZi7x29FEk8yIZez55g5tDMbipDLRFPNulpJIQ.npH8M-QCiMXWUftYJ0Gw0htfHK06LFz9aa27GwH-CIw", "validationRecord": [ { "url": "http://example.com/.well-known/acme-challenge/4LnkxboZi7x29FEk8yIZez9g5tDMbipDLRFPNulpJIQ", "hostname": "example.com", "port": "80", "addressesResolved": [ "93.184.111.222", "2606:2800:220:1:248:334:25c8:1946" ], "addressUsed": "2606:2800:220:1:248:456:25c8:1946", "addressesTried": [] } ] }