That doesn't solve the problem.
If you call my own server with the ip: 126.96.36.199 you see a page stating that the server works.
If you try the same with the new server with the ip: 188.8.131.52 you'll get the error 403.
In my opinion that has nothing to do with DNS, because the default site shouild be presented at direct ip call. It does with my own server, but not with the new one.
Both servers are ISpconfig3 but different ubuntu's.