WPMU Dev Dashboard will not connect via our multisite instance

We have been using WPMU for several years. Our membership recently expired, and when we reactivated, the Dashboard plugin needed to be updated. Now, when I try to log into WPMU from the our multisite instance (Network Admin —> WPMU DEv —> log in screen for WPMU dev), I get this error:

Your server had a problem connecting to WPMU DEV: “SSLRead() return error -9806”. 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?”

We are using a Mac OS 10.10.5 server with CURL enabled. Can you help?