OK, I've sorted this out now - it was a DNS problem with my router. I was using DNS alternatives to my ISPs and for reasons I really don't understand, the alternatives wouldn't resolve the domain name. Very odd and never had a problem with it before. Thanks for the help. Time to update the custom firmware on my Hummy!
First obvious problem I've had with them in over a year and only mildly irritating but irritating nonetheless. I think we might be drifting a bit off-topic here though, so I'll stop. Only just joined the forum!