Hm if you have Zscaler, open that app and turn off internet security and try again. Either that, or add the proper certificates using stuff like keystore. Turning off the security is temporary and it automatically reengages after a few minutes.
Is the error message you provided the full message?
Or instead upgrade to 10.12.4 since that is the current LTS, see if you still have this problem and if so, raise a ticket to Mendix (support.mendix.com).