Hi @arcenas090,
Indeed there is some proxy, filtering content application, etc. ...so, as @mnordhoff said, there is something filtering the connection and if the client used to access the validation file doesn't support javascript, then, can't get the validation file.
1.- If you try to reach the file http://knowledge.infinityhoster.ga/.well-known/acme-challenge/YprpgbmK4etqO70iC2GVnfDyGkJpluZuVxJLk2xMNTo
using a desktop or mobile browser you get the right file with the right content.
2.- If you try to use curl
from the command line (this is closest to how Let's Encrypt connects to your site) you get a Forbidden message.
$ curl -ikL http://knowledge.infinityhoster.ga/.well-known/acme-challenge/YprpgbmK4etqO70iC2GVnfDyGkJpluZuVxJLk2xMNTo
HTTP/1.1 403 Forbidden
Server: nginx
Date: Sat, 24 Mar 2018 07:58:47 GMT
Content-Type: text/html
Content-Length: 162
Connection: keep-alive
Vary: Accept-Encoding
<html>
<head><title>403 Forbidden</title></head>
<body bgcolor="white">
<center><h1>403 Forbidden</h1></center>
<hr><center>nginx</center>
</body>
</html>
3.- Now let's try to simulate that we are Let's Encrypt using another User Agent in the curl
connection:
$ curl -ikL -A "Mozilla/5.0 (compatible; Let's Encrypt validation server; +https://www.letsencrypt.org)" http://knowledge.infinityhoster.ga/.well-known/acme-challenge/YprpgbmK4etqO70iC2GVnfDyGkJpluZuVxJLk2xMNTo
HTTP/1.1 200 OK
Server: nginx
Date: Sat, 24 Mar 2018 07:58:36 GMT
Content-Type: text/html
Content-Length: 908
Connection: keep-alive
Vary: Accept-Encoding
Expires: Thu, 01 Jan 1970 00:00:01 GMT
Cache-Control: no-cache
<html><body><script type="text/javascript" src="/aes.js" ></script><script>function toNumbers(d){var e=[];d.replace(/(..)/g,function(d){e.push(parseInt(d,16))});return e}function toHex(){for(var d=[],d=1==arguments.length&&arguments[0].constructor==Array?arguments[0]:arguments,e="",f=0;f<d.length;f++)e+=(16>d[f]?"0":"")+d[f].toString(16);return e.toLowerCase()}var a=toNumbers("f655ba9d09a112d4968c63579db590b4"),b=toNumbers("98344c2eee86c3994890592585b49f80"),c=toNumbers("677790d20f90e13356c6b0586b196191");document.cookie="__test="+toHex(slowAES.decrypt(c,2,a,b))+"; expires=Thu, 31-Dec-37 23:55:55 GMT; path=/"; location.href="http://knowledge.infinityhoster.ga/.well-known/acme-challenge/YprpgbmK4etqO70iC2GVnfDyGkJpluZuVxJLk2xMNTo?i=1";</script><noscript>This site requires Javascript to work, please enable Javascript in your browser or use a browser with Javascript support</noscript></body></html>⏎
So, there is something in the middle of your connection and only allows to access your site if the client used supports javascript and Let's Encrypt doesn't.
Good luck,
sahsanu