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:”. 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 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?