Hello,
I try to set your "Domain Name System (DNS)" to my wifi router. It all set and i can see the dns names in iphone wifi when it connected.. But it not filtering as you said. like Security + Pornography + Other.
I have used..Policy 3: Security + Pornography + Other (199.85.126.30 and 199.85.127.30) "Policy 3, you should configure the DNS settings of your home router or Web-enabled device to use the following Norton ConnectSafe IP addresses: 199.85.126.30 and199.85.127.30."
Got information from Dns ... https://dns.norton.com/faq.html