Jessie on Orange Pi Plus 2

I did want to add that while I agree MQTT is the best solution here, for this specific install issue, it can be worked around with the steps in this post: Installing Cayenne - #7 by rsiegel

It seems to occur now and then on even Raspberry Pi devices, and I suspect a configuration issue on the device side rather than any issue with the certificate on our server – but the check can be ignored using those steps.