Noticed my Nests were down earlier. They are back up now.

As far as working "fine" offline, I have another gripe about my Nest thermostats: Why is the sample rate on the temperature so damn slow? One of my zones is a small (~500 sq/ft) room and the HVAC can move the temperature there rather quickly. What always happens is the heat/cool usually stays on well beyond the desired set point. This is because the device does not sample the temperature often enough. If the mode is set to heat & cool, the heat and AC will both oscillate on and off forever unless the min and max are more than 5 degrees apart. It's not a matter of the Nest sensor lagging because of its heat capacity because I have tried a heat gun and freeze spray to observe the sample rate. It really sucks.

I think what api is referring to is there isn't a good reason why you shouldn't be able to use your phone to adjust your thermostat on your local network without leaving the internal network.