If they know your real ip, then they will attack directly to your server. So cloudflare and the others will not help much. Because they only for ddos attack layer 7.
So the solution is:
1. Change your public IP.
2. Install fail2ban because this will help for ddos layer 4 attack.
3. Install SSL in your server.
4. Close all port and open only needed port in your firewall server.
5. Make sure your web server is using NGINX
6. Make sure your database server separated with your web server.
7. Rate limit request to server with redis cache.
Actualy there is a lot, but I can not explain detail because you dont write what have you done for security and what is spesification server you are using.