Devices that work when the internet dies

The real test of a local-first smart home is what happens when your internet goes down. Not the marketing claims. Not the spec sheet. What actually keeps working when the router loses its upstream connection.

We have tested this across a lot of devices, and the results aren’t always what you expect.

The general rule

Devices that talk directly to a local hub over Zigbee, Z-Wave, or Thread will generally keep working. Devices that depend on a vendor cloud for command processing, automation logic, or device communication will generally stop being smart.

Your smart home’s offline behavior depends less on the individual devices and more on where the brains live. If your automations run on Home Assistant inside your home, they keep running. If they run on a server in Virginia, they don’t.

What works well offline

Zigbee and Z-Wave devices with Home Assistant

This is the strongest offline story. Zigbee sensors, switches, plugs, and lights paired to a local coordinator and automated through Home Assistant keep working exactly as they did before the internet went down. The mesh is local, the hub is local, the automations are local.

Devices worth highlighting:

Zigbee motion sensors and contact sensors — automations keep firing
Zigbee and Z-Wave light switches — full local control, no cloud dependency
Z-Wave locks — lock/unlock commands work through Home Assistant
Zigbee smart plugs — on/off and energy monitoring stay local
Aqara FP2 and FP1 presence sensors — continue working via local integration

The coordinator is the critical piece here. A good Zigbee coordinator paired with Home Assistant gives you the most resilient local setup.

ESPHome devices

Devices running ESPHome firmware are fully local by design. They connect to Home Assistant over your local Wi-Fi network and never touch a cloud server. When the internet goes down, they don’t even notice.

The Everything Presence One is a good example — mmWave presence detection that is completely local.

HomeKit devices with an Apple home hub

Apple HomeKit automations run locally on your HomePod, HomePod Mini, or Apple TV. If your internet goes down but your local network stays up, HomeKit automations keep running and you can still control devices from your phone (as long as you’re on the same local network).

The Schlage Encode Plus is a strong example — HomeKit local control keeps working without internet.

What partially works

Wi-Fi devices with local APIs

Some Wi-Fi devices have local APIs or local control modes that work without internet, but with reduced functionality. Shelly devices, for example, have excellent local HTTP APIs and work great with Home Assistant locally. Tuya devices flashed with custom firmware can work locally. Stock Tuya devices without firmware modifications are mostly cloud-dependent.

The pattern: if the device supports a local API or local protocol that Home Assistant can talk to directly, it usually keeps working. If Home Assistant has to go through a cloud bridge, it doesn’t.

Smart locks

Locks are complicated. Most smart locks will still lock and unlock physically regardless of connectivity. But the “smart” features vary:

Z-Wave or Zigbee locks controlled through Home Assistant — smart features keep working locally
Wi-Fi locks like August — the lock works mechanically, but app-based smart features may not
Bluetooth locks — work if your phone is nearby, but remote and automation features are limited

See our smart lock guide for more detail on local control realities.

What stops working

Cloud-dependent voice assistants

Alexa and Google Assistant stop processing commands when the internet is down. Your Echo and Google Home speakers become Bluetooth speakers (if that). Voice-triggered automations that run through these platforms stop entirely.

This is the single biggest failure mode in homes that build their whole automation stack around Alexa routines or Google Home automations.

Cloud-only cameras

Cameras that stream exclusively through vendor clouds (Ring, most Blink cameras, cloud-only Wyze setups) lose their smart features. They may continue recording to a local SD card if they have one, but you lose remote viewing, notifications, and cloud-based detection.

Cameras with RTSP or ONVIF support that stream to a local NVR (like Frigate on Home Assistant) keep working fine.

Cloud-dependent smart plugs and switches

Cheap Wi-Fi smart plugs that only work through a vendor app (Tuya cloud, Smart Life, etc.) stop responding to app commands. The device itself stays in whatever state it was in, but you can’t control it remotely or trigger automations.

Vendor-bridged integrations

Any integration where Home Assistant talks to a vendor’s cloud to reach the device fails when the internet goes down. This includes many popular integrations: stock Tuya, Ring, Nest (some features), and others.

How to audit your own setup

Here is a practical test:

Unplug your internet connection (just the WAN cable from your router, keep your local network running)
Wait a few minutes for cloud connections to time out
Walk through your house and test every automation and device
Note what works, what is degraded, and what is dead

Do this before you need it, not during an actual outage. It’s revealing.

Building for resilience

The pattern is straightforward:

Use Home Assistant as your automation engine — it runs locally
Prefer Zigbee, Z-Wave, or Thread devices — they talk to local coordinators
Use ESPHome for custom devices — fully local by design
Avoid building critical automations on cloud-dependent platforms
Keep voice assistants as a convenience layer, not the foundation

You don’t need to be paranoid about this. Some cloud features are fine for non-critical things. But your lights, locks, climate control, and security automations should work without the internet. That is the baseline.