Home Assistant runs locally on your own device, so most of it works without internet — but not all of it

Home Assistant is software that runs on a computer or device in your home, not on someone else's server. Because it lives on your hardware and controls things physically connected to your network, the core functions — turning lights on and off, adjusting thermostats, locking doors — keep working when your internet connection drops. You lose the ability to control your home from outside the house, and some features stop working, but the system itself does not shut down.

The catch is that Home Assistant has become more complex over time. Some integrations (the connections to your smart devices) need the internet to work at all. Others work locally but lose features when offline. Understanding which parts of your setup will survive an outage means knowing what you have connected and how each piece communicates.

Key Takeaways

  • Local automations and device control work without internet as long as your devices stay connected to your home network.
  • Cloud-dependent integrations like Google Home, Alexa, and many commercial smart home services stop working during an outage.
  • Remote access from outside your home requires internet on both ends, so you cannot control anything from your phone when your connection is down.
  • Some devices need their own local connection method (like Zigbee or Z-Wave) to work without internet, while others only talk to the cloud.
  • Testing your setup before an outage happens is the only way to know what will and will not work when the internet actually fails.

What keeps working when internet drops

If you have set up automations that run on a schedule or respond to local sensors, those continue to run. An automation that turns on lights at sunset, or one that adjusts your thermostat based on a temperature sensor in your hallway, does not need the internet to function. Home Assistant checks the time and reads the sensor data from devices on your local network, then sends the command to turn the light on or change the temperature. None of that traffic leaves your house.

Manual control through the Home Assistant interface also works as long as you are on the same Wi-Fi network. If you open the Home Assistant app or web interface on a phone or tablet connected to your home network, you can still toggle switches, adjust sliders, and see the status of your devices. The communication happens between your phone and the Home Assistant device, both on your local network, so no internet is required.

Devices that communicate using local protocols like Zigbee or Z-Wave are unaffected by internet outages. These devices talk directly to a hub or receiver in your home using their own radio frequencies. Home Assistant receives the data from that hub and acts on it. As long as the hub and Home Assistant device are powered and connected to each other, the system works.

What stops working without internet

Any integration that relies on a cloud service becomes unavailable. If you use Google Home, Amazon Alexa, Apple Siri, or IFTTT to control your Home Assistant setup, those connections break. You cannot ask your smart speaker to turn on the lights because the speaker cannot reach the cloud service that talks to Home Assistant. The reverse is also true — Home Assistant cannot send data to those services.

Weather integrations that pull data from online weather services stop updating. Your Home Assistant dashboard will show the last known weather information, but it will not refresh until the internet comes back. Some people use weather data to trigger automations (like closing blinds when it gets too hot), so those automations may not work as expected if the weather data is stale.

Notifications sent through cloud services fail. If you have set up automations to send you a notification through Telegram, Discord, or email when something happens, those messages will not go out while you are offline. The automation itself may still run, but the notification step fails silently.

Remote access stops working. You cannot open the Home Assistant app from outside your home and control anything. Some people set up a VPN or a reverse proxy to access Home Assistant remotely, and those methods also require internet on your end to work.

Devices that need internet even for local control

Many commercial smart home devices — including some smart plugs, bulbs, and cameras from major manufacturers — only communicate through the cloud. They do not have a local control option built in. Even though Home Assistant is running locally, it cannot talk to these devices without the internet because the devices themselves do not listen for local commands. They only accept instructions from their manufacturer's cloud service.

Before you buy a smart device, check whether it supports local control. Look for phrases like "local API", "local control", "works offline", or "Zigbee/Z-Wave compatible". Devices from manufacturers like Philips Hue, IKEA Tradfri, and Sonoff often have local options, while some budget brands and newer devices may not.

If you already own devices that only work through the cloud, you have two choices: accept that they will not work during an outage, or gradually replace them with devices that support local control. Home Assistant's community maintains a list of devices known to work locally, which can help guide replacement decisions.

How to test your setup before an outage

The most reliable way to know what will work is to unplug your internet router and see what happens. Leave it unplugged for at least 10 minutes so your devices fully disconnect from the internet. Then try the things you rely on: toggle lights, check automations, look at your dashboard. Write down what works and what does not.

If you do not want to disconnect your whole network, you can isolate Home Assistant instead. Some routers let you block a specific device from accessing the internet while keeping everything else online. Check your router's settings for a feature called "block internet access", "offline mode", or "guest network isolation". Put Home Assistant on that blocked list, then test.

Pay special attention to automations that matter. If you have an automation that unlocks your front door at a certain time, or one that turns on lights when motion is detected, test it during the outage. If it fails, you know you need to find a local alternative or accept that it will not work during an outage.

Building a setup that works offline

If you want Home Assistant to be as useful as possible without internet, prioritize devices with local control options. Zigbee and Z-Wave devices are the most reliable because they have their own network separate from Wi-Fi and do not depend on cloud services. A Zigbee hub or Z-Wave controller plugged into Home Assistant gives you access to hundreds of compatible devices.

For Wi-Fi devices, look for ones that support local control through an open protocol. Some devices work with Home Assistant's local API, which means Home Assistant can send commands directly without going through the cloud. The Home Assistant documentation lists integrations that work locally, organized by device type.

Avoid building automations that depend on cloud services if you want them to work offline. Instead of using a cloud weather service to trigger an automation, use a local sensor. Instead of sending notifications through a cloud service, use a local notification method like a speaker or a display connected to your network.

What happens to Home Assistant itself during an outage

Home Assistant does not need internet to run. The software itself does not phone home, check for updates, or validate your setup with a remote server. It runs entirely on the device you installed it on. As long as that device has power and is connected to your local network, Home Assistant keeps running.

Updates and add-ons that depend on downloading files from the internet will not work during an outage. If you try to install a new integration or update Home Assistant while offline, it will fail. But the existing setup keeps running without interruption.

Some people use Home Assistant Cloud, a paid service from the Home Assistant team that provides remote access and other features. If you subscribe to that service, it stops working during an outage because it relies on the internet. But the local Home Assistant installation itself is unaffected.

Frequently Asked Questions

Can I control Home Assistant from my phone if I am away from home?

Not without internet on both ends. You need internet at home so Home Assistant can receive your commands, and you need internet on your phone to send them. Some people set up a VPN to their home network, which lets them access Home Assistant remotely, but that also requires internet on both sides.

Will my smart lights work if the internet goes out?

It depends on the lights. Zigbee and Z-Wave lights work fine. Wi-Fi lights that support local control work fine. Wi-Fi lights that only work through the cloud do not work at all. Check your light's documentation or test during an outage to know for sure.

Do I need to do anything special to prepare Home Assistant for an outage?

Test your setup by disconnecting the internet and seeing what works. Make a list of what you need to work offline, and replace any devices that do not support local control. After that, Home Assistant requires no special preparation — it will keep running as long as it has power and a local network connection.

What if my Home Assistant device loses power during an outage?

It stops working entirely. If you want Home Assistant to keep running during a power outage, you need an uninterruptible power supply (UPS) connected to the device. A UPS is a battery backup that keeps your device running for a limited time when the power goes out.

Can I use Home Assistant without setting up remote access?

Yes. Many people run Home Assistant only for local control and automations, and never set up remote access. They control it from their phone or tablet while at home on the Wi-Fi network. This setup is simpler and works fine during internet outages.