I would like to know if the SmartThings hub will function without an active connection to the Samsung servers?
Smartthings has been designed from the beginning as a cloud-based system.
At the present time, the only rules which can run locally are those created through the official “smart lighting“ feature and a small bit of smart home monitor. Even the official routines cannot run locally.
And only some devices are eligible to run locally: the ones which are using the stock device type handlers. They have been adding more of these over time, but it’s still a limited set.
At the present time, all custom code, whether it is for a smart app or a device type handler, must have a connection to the cloud in order to run. That includes the very popular rules engine, WebCoRE.
So it would be possible to design a SmartThings set up which included only GE light switches, some specific sensors, and some plug-in modules, and create rules only through the official smart lighting feature, and have all of that run even if your Internet was out.
But that’s not how most people have their smartthings accounts set up. ( as I mentioned, even just running a routine will require a cloud connection.) Just as one example, you can’t operate your smart locks locally. You also can’t arm/disarm the smart home monitor features unless you have a cloud connection. And you can’t change home automation modes, including recognizing “home“ and “away“ unless you have a cloud connection.
In fact, you can’t use the official smartthings mobile app at all, even to toggle switch on and off, without a cloud connection because the app talks to the cloud and then the cloud talks to the hub even if the phone is on the same LAN as the hub. It’s just the way the architecture is designed. This also means you will not receive any notifications when the cloud is not available.
https://support.smartthings.com/hc/en-us/articles/209979766-Local-processing
Since the mobile app itself is completely useless without a cloud connection, I think most people from a practical standpoint would say the system doesn’t run locally. But technically, as I mentioned, you could set it up so that the closet light comes on every time the closet door is opened and have that run locally using SmartLighting.
I know that’s a long answer, but as delivered, “local processing“ turned out to be very different than what most people expected it to be, and there are just a lot of footnotes to the way it operates.
One additional footnote: the new ADT/SmartThings security panel, introduced in the fall of 2017, can use the new ADT/smartthings dual logo sensors locally and has its own cellular communications module which can call the ADT monitoring center. But none of the home automation rules, including the smartthings mobile app, will run locally and none of the other notifications can use the cellular module. And the cellular module is only available with that specific panel and only when you pay for the ADT service. So there are some additional security functions for that specific model of the hub that run locally, but not many.