What breaks when your internet goes down?
Pick your platform, check what you own, and see the honest answer for each item. Nothing you enter leaves your browser.
How the verdicts are decided#
Each item you check is classified by where its control path runs:
| Class | Examples | Outage behavior |
|---|---|---|
| Locally controlled | Matter over Thread, Zigbee and Z-Wave devices on a local hub, Lutron Caseta, Hue on its bridge | Works if your platform executes locally. Degraded if the platform is cloud based. |
| Cloud only by design | Wi-Fi devices with a brand app, cloud cameras, most robot vacuums | Stops. There is no local fallback to fall back to. |
| Voice | Any smart speaker | Wake word detection is local, speech recognition normally is not. Only Home Assistant offers a fully local pipeline. |
| Mixed | Smart locks, cloud thermostats | The device keeps doing its primary job. Remote access, notifications and schedules that depend on the vendor stop. |
The platform half of the calculation comes from the Local Control Index, which scores every platform out of 100 on eight criteria. The spread is dramatic: from 100 down to single digits.
What to do with the result#
- If the score is low and you care, the highest-leverage change is usually not replacing devices. It is moving automation execution to something that runs locally, then keeping cloud devices for convenience rather than for anything on the critical path.
- Start with the critical path. Stairway lights, the thermostat in February, the garage door, and anything that locks. If those fail during an outage, that is worth money to fix. A cloud-connected coffee maker is not.
- Check the physical fallback. Every smart switch should still work as a switch. Every lock should still work with a key or a code. If any device fails that test, it is a single point of failure regardless of protocol.
Full detail on the reasoning is in what still works when the internet goes down, and the design principles are in local versus cloud control.
If my devices use Matter, are they local?
Not necessarily. Matter defines local communication between a controller and a device, but your platform decides whether it acts on that locally or sends the command to its servers first. Google Home's local Matter control, for example, covers lights, plugs and switches and not much else.
Does a hub guarantee local control?
No. A hub gives you a local radio, which is necessary but not sufficient. The question is whether the automation engine and the app also run locally. Some hubs are essentially cloud terminals with a radio attached.
What about power cuts rather than internet cuts?
Different problem, worse outcome. In a power cut everything mains-powered stops, including your hub, your router and your Wi-Fi devices. Battery sensors keep transmitting into a void. If you want anything to survive a power cut, the hub and the router need a small uninterruptible power supply, which is a cheaper upgrade than most people expect.
Which platform is best if outage resilience is my priority?
Home Assistant, then Hubitat. Both run automations on hardware in your house with no vendor in the loop. Everything else involves an explicit trade, which the platform picker will weigh for your situation.