Ideally you need mod_cloudflare
installed on the server, this allows Apache to pass on the IP of the user to phpBB, logging or anything else. Without it everything will logged as Cloudflare's IP's. Easiest way to check if it's installed is go to the online list and check that your IP is not Cloudflare IP.
If you do not have mod_cloudflare installed or your host will not install it there is an extension but this only works with phpBB. Server logs and other things will still list Cloudflare IP's.
https://www.phpbb.com/customise/db/exte ... masked_ip/