When using Railgun (or other reverse proxy software, such as Varnish), user's requests will come from your Railgun server instead of Cloudflare. Because request's are not coming directly from Cloudflare, mod_cloudflare will not restore visitor IP addresses by default.
To fix this, open up your Apache configuration (this can typically be found in /etc/apache2/apache2.conf, /etc/httpd/httpd.conf, /usr/local/apache/conf/httpd.conf or another location depending on configuration, if you're unsure ask your hosting provider) and at the very end add:
So, if your Railgun server is located at 127.0.0.1, it will look like:
If you have more than one server to add to the trusted proxy list, you can add them at the end:
CloudflareRemoteIPTrustedProxy 127.0.0.1 127.0.0.2