Can't connect to WPMUDEV

I'm getting this error when connecting a site...

Your server had a problem connecting to WPMU DEV: "cURL error 6: Could not resolve host: premium.wpmudev.org". Please try again.

If this problem continues, please contact your host with this error message and ask:

"Is php on my server properly configured to be able to contact https://premium.wpmudev.org/api/dashboard/v1/ with a POST HTTP request via fsockopen or CURL?"

I've not contacted my host yet as I know I've got another site on the same host that is working fine – any other ideas before I get in touch?

Jon