Sorry, I still don't quite understand what you are trying very hard to say.
If I understand you correctly, you have a dedicated server supplied by a hosting company.
You installed XAMPP on this dedicated server.
What Operating System is this dedicated server using?
Does XAMPP, that is, does Apache, MySQL, PHP and Perl work without issue?
Your dedicated host tells you that you are being attacked by a DDoS.
What is your hosting provider, through the Data Center the dedicated server is located, doing about the DDoS attacks?
There is not much you can do about a DDoS attack as you don't have access at the level that can effect a DDoS attack deterrent.
This must be done at the Data Center level of access.
They have means to help in this matter and know exactly what to do.
Now if you are talking about XAMPP that is installed on your home PC then just stop Apache and look in your log files for the range of IPs that are attacking you and then ban those IPs in your PC's firewall from accessing your PC on TCP port 80
Let me know if I have hit the mark and have understood you concerns.
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