I just had a internet outage and it made me wonder is there a way i will be able to run all my connected devices while the internet is down? For a little while i had no internet but the devices were going even the cloud based ones but once the hub went offline that was the end of it. Is there a way to make it work without internet or is this something that is still coming?
SmartThings is still primarily a cloud-based system. And thereâs no reason to believe that will ever change.
Some Devices and some rules can run locally without the Internet, but not as many as you might think.
For example, you have to have the Internet in order to use the app to control anything. The app always talks to your cloud account, not directly to your hub, even if they are on the same Wi-Fi. The app talks to the cloud, the cloud talks to the hub. So if your Internet is out, you canât use the app at all. (they didnât have to design it that way, but they did, and theyâve kept it that way for more than five years.)
Some information is stored in your cloud account. So you canât change the mode at all or arm/disarm the security status unless the cloud is available.
https://support.smartthings.com/hc/en-us/articles/209979766-Local-processing#What
You can find many discussions in the forum about exactly what runs locally, but basically itâs the official smart lighting feature and some bits of smart home monitor. And again only with some devices and only with the stock device type handlers.
If you need a system that can run when the Internet is out, youâll need to look at some of the competition. There are a number of systems to choose from.
But as far as smartthings goes, it needs the cloud.
If you want to list the specific brand and model of the devices that you have, someone could probably tell you if thatâs a candidate for the smart lighting features that run locally. But again remember that you wonât be able to use the app or change the mode regardless of what device you have.
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Well what i was hoping was my motion sensors could trigger a siren even if the internet was down which does use smart home monitor. But theyâre all cloud based as im using device handlers for them. I donât suppose when they bring out the new Rules api stuff out it might work?
âIn the event of an internet and/or power outage, a SmartThings Home Monitor automation that tells your Aeon Labs Siren to sound when motion is detected by a Samsung SmartThings Motion Sensor will locally execute.â
This is sort of what i wanted to do⌠are there any other motion sensors that work locally?
Same for voice assistants such as Alexa and Google Home, right?
Alexa now offers some local voice control, but again, not much. Only for zigbee devices connected directly to an Echo plus or Echo Show 2nd generation.
https://www.amazon.com/gp/help/customer/display.html?nodeId=GCC6XV9DX58VW5YW
At our house, because voice control is so critical (Iâm quadriparetic), we do have two light switches set up this way so I could get from my room to the front door or vice versa at night with voice control even if the Internet is out. (Although the power would still have to be on, of course.)
For most people, voice is only one of several control methods. If voice was not available but the app still worked, they could at least operate devices that way.
Probably more Important for both groups, though, is that automations would still work in a local system. I use HomeKit, which is local. If the internet goes out, my lights still come on on a timed schedule, my motion sensors still trigger my lights and my door lock (from inside the house), my temperature sensor still triggers my ceiling fan. And all of my button remotes still work. If I were using Iota, my security system could still be armed automatically when I left the house. Or disarmed automatically when I got home.
So while voice control is important to many households, itâs not the same as losing the ability to turn lights on and off.
Or most annoyingly, having no mechanism to disarm the security system OR turn off the siren which goes off because you couldnât disarm the security system. 
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You CAN do that with some sirens, but you have to think about the possible results because in SmartThings you CANNOT disarm the security system if the internet is out. Which means the motion sensor will keep setting that siren off until you take one of them off power.
This exact scenario has happened to multiple community members before. And it usually happens when the family member who does the tech support is still at work. Or it happens to the kids when they get home from school.
Because there is no way to disarm the security features if the cloud is unavailable, and the app and tablets wonât work, all you can do is take one of the two devices off power. Then remember to put the batteries back in when cloud access is restored. 
Itâs not what most people want from a smart home security siren. Just sayinââŚ
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Yep, happened to my house sitter. The internet was out when they arrived so they couldnât disarm the system, the siren was triggered when they opened the door, and they couldnât turn the siren off. They also couldnât reach me since I was out of country in a remote area with no cell service. They eventually figured out how to remove the batteries from the siren.
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I donât mind too much about the motion sensors setting it off and not being able to turn it off. Thats sort of what i want anyway⌠i was looking at the list and i found a couple of the device handlers would work with my motion sensors and make them local, but the âexcution localâ is false so thats not going to work without internet either is it?
Have you thought about minimizing the chances of an internet outage?
I use a failover modem (Netgear LB2120) between my hub and the dsl modem. Whenever the dsl goes out or the modem has to be rebooted, the failover switches to LTE, usually before the hub has a chance to notice the outage.
You would have to choose a cost effective SIM which may be easier said than done. I have a Google fi phone so I use one of their data-only SIMs. It doesnât have a monthly fee so I only pay for extra data, but it doesnât include sms so I donât get failover notifications.
Yeah i want to do that too⌠the isp im with here in Aus doesnât have a mobile backup modem right now so getting a prepaid thing happening might be an option
If you accident triggered the alarm or opened a door to come home not knowing there was an outage how would you disable the alarm if it was triggered.
Iâve thought about this quite a bit and tbh Iâd much rather have it not trigger in this case. Especially having a new born. Donât fancy him competing with the siren to see who could scream loudest 
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Hi @JDRoberts, I have Smartthings Home Monitor (new App) configured to trigger when it detects movement or when open a door, for this I use 3 movement sensors (smartthings) and 5 contact sensors (ecolink), all run locally (verified in IDE), just like a local execution Siren (AEON). However I canât get it to work when I donât have internet. I am doing something wrong? Could you help me with an example of how STHM should be configured to activate without internet.
Thanks
Is the security.mode active before the Internet goes off?
Yes, the STHM is Armed (away) or Armed (home)
Iâm sorry, Iâm not that familiar with the new V3 app. I would try contacting support.
Ok, Thanks
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Has anyone come across what @cljara80 was experiencing? Iâm having the same issues. I meet all the requirements of local processing (https://support.smartthings.com/hc/en-us/articles/209979766-Local-processing), my devices can all do local as per IDE, Iâm using SmartThings Home Monitor, i have the current hub, but when the internet goes, local processing does not work.
In the classic app, some parts of the security features, SHM (smart home monitor), could run locally.
Based on community member reports, this has been removed in the new V3 app, where the security feature is STHM (smartthings home monitor).
During the migration, several community members have reported that security automations in SHM which ran locally now are cloud based in STHM.
So it looks like as of this writing only automations created in the official smartlighting feature are eligible to run locally. The security features no longer are. 
The support article appears to be based on the classic feature. they just changed the name but didnât note the change in functionality.
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Hi my friend, so basically If user wants a local security system (no depending of internet) its has to be âprogrammedâ with local devices drivers and automations that simulate a STHMâŚ? Am I right ?