What does and doesn't work when an ST hub has no internet?

I have a SmartThings (v3) hub and all of our Z-Wave and Zigbee devices have been migrated to Edge drivers running directly on the hub.

Recently we had an extended internet outage yet most of our routines were able to run locally. Outdoor lights came on when expected, closet doors opening turned on lights, etc.

There are several things that didn’t work however. Clearly notifications didn’t work because they go out through the hub to the Samsung servers to send a message to the app. Also, the app goes through the servers to query status so the app was essentially unusable. Similarly, voice control via something like Google Assistant didn’t work because that needs to talk to the hub but it sees everything as offline.

Can anyone add to this based on what they’ve experienced or know about this?

In particular, does anyone know if the hub is able to do its own sunset/sunrise time calculations or is it always getting that fed from the servers?

The lighting routines that used sunrise/sunset still worked but I wonder if the data would eventually be stale, if the hub was completely local for a long period of time?

And a similar question about time changes for daylight saving time. Is that done locally on the hub? Or does it use NTP perhaps? Or is it dependent on Samsung servers?

This is a list of things I have found that cause Routines to run in the cloud:

   * Scenes
   * Lighting Groups
   * Member Location
   * Devices from cloud->cloud integrations
   * Notification actions
   * Weather triggers
   * STHM triggers and actions
   * " Any Day" time precondition
   * Cloud virtual devices
   * Devices on two different hubs

Good question which has been discussed many times, you can find quite a few forum threads on it.

There’s a front line answer, and a back platform answer.

The front line answer is obvious and testable by any customer. The app always requires the cloud. Notifications always require the cloud. Some routines (not all) will require the cloud depending on the exact details. Some virtual devices, but not all, run in the cloud. If you are using more than one hub, and you have a routine with devices from different hubs, that will require the cloud.

Official documentation on this is incomplete, but @h0ckeysk8er has a list of conditions that will cause a routine to run in the cloud.

And of course, any third-party cloud-based integration, including all of the voice assistants, will require the cloud.

The back platform answer isn’t obvious and isn’t documented, but smartthings engineers have said that the system is still primarily cloud-based, and assumes that the hub will be connected to the cloud most of the time to synchronize a number of things. It might run for a few hours when the power is out, but after that things can start to get wonky. Your question about sunset time falls into this: that is, indeed set in the cloud and updated every day, so it will get out of sync quite quickly. But other things as well. We just don’t know exactly which.

All smartthings “services” require the cloud, including SmartThings Home Monitor, as do Samsung smart appliances and televisions.

Here’s the official schematic for the new platform: as you can see, the cloud is still dominant.

You can find additional threads about this by searching for “local processing.“

on the smartthings platform the voice assistant does not talk to the hub. Your voice assistant talks to its cloud, its cloud talks to the smartthings cloud, and the smartthings cloud sends the necessary instructions to the hub or to any of your cloud-connected devices.

Okay, not directly but we are both making the same point that voice assistants are in the cloud and need the hub connected to the internet in order to get devices to activate.

1 Like

That makes me ask a related question. Are there any ways to talk directly on WiFi to the hub? Say a locally hosted dashboard or app?

Yes. See the quick Browse list for “edge services” for some examples of projects community members have created. :sunglasses: It requires some technical expertise, but it’s definitely doable under the new architecture.


Hi @JDRoberts The hub must know when it has to initiate a cloud routine and can’t get a connection. Is there any kind of a retry mechanism that maybe has a time limit/# tries or does it just fail immediately and silently (it really should indicate something in the history)?

Did anyone ever put in a feature request for this?

1 Like

It will try a couple of times, but I don’t know how many, and it won’t be for very long.

I think most of the time the routine that needs the cloud would be initiated in the cloud, but again I don’t know the details.

I also don’t know if there’s any record kept in the logs or not. :thinking:

There’s not. I had a cloud routine fail to run at 11AM today and there was nothing in History. The ones that ran were logged, not the ones that did not run.

1 Like

Oh and also it must not have been offline for very long, since I never got a “hub offline” message. Seems like ST makes a most feeble attempt to run the routine.

1 Like