The Pi is at pi.johnj.info I use Zone Edit and dynamic dns to keep the subdomain pointing at my home network when its external IP address changes.
This stopped working. It looks like
A Dynamic Authentication Token is required in order to use our Dynamic DNS services. The tokens are generated on a per domain basis.
This is used in the place of my zoneedit password which used to work.
Fix found Solved: Re: BT Home Hub 5 Dynamic DNS – BTCare Community Forums via google.