I have just set up a router running pfSense on our network and forwarded the appropriate ports. I have a small web server running in my network, and a domain name pointing to our (WAN) IP. When accessing that domain name, everything works fine. However, when accessing a subdomain of the domain name, pfSense will give a DNS rebinding warning. This did not happen back when I used a DD-WRT router. What is the proper way to fix this? The DNS records for the subdomain also point to the same address (I use a virtual server to differentiate the subdomains.)