I've decided to use Norton SafeConnect https://dns.norton.com/homeuser.html
to provide DNS settings but the ttb DNS Check (in Tools) still shows :-
"Warning! We detected your IP address as 109.xxx.xxx.x and found an open DNS resolver running.
This may be either running on your computer or on your broadband router. It is advisable that you don't run a resolver which can be queried from the Internet. It is possible that you could be vulnerable to a DNS poisoning attack. .........."
This happens with settings applied to both computer and wired router.
Has anyone else found this?