Broadband drops. A digger goes through a cable, the router needs a restart, the provider has a bad evening. In a lot of smart homes that is the moment the lights stop answering the app, the heating app cannot reach the thermostat and the camera app shows a spinning wheel.
It does not have to be like that. Whether a smart home carries on through an outage depends on one thing: where each decision is made.
Why so many smart homes stop
Tap a light in many smart home apps and the instruction leaves your house for the maker's servers, then comes back in again to a bulb a few metres from your phone. When the internet goes, that round trip breaks, even though the phone and the bulb are in the same room.
A locally run home makes the decision in the house. Your phone talks to the hub over your own Wi-Fi, and the hub talks to the devices directly. Devices on open standards such as Zigbee, Matter and Thread answer to the hub, not to a cloud, so they carry on when the internet does not.
What keeps working with the broadband off
In the homes we fit, everything that matters runs on the hub, a compact computer that sits beside your router. With the internet down:
The cameras keep recording to the hub and keep telling people from cars and animals.
The alarm keeps watching in Home, Night or Away. If a watched door opens, the countdown runs, the sirens sound, the lights we wire in with you come on and every camera saves the moment.
The heating keeps its plan, room by room where thermostats are fitted, and phones in the house can still change it.
Automations and scenes run on the hub's own clock: the porch light at sunset, the heating at 06:45, Cinema from the sofa.
Voice still answers for the house, because the listening and the understanding happen on the hub: the lights, a scene, "what's open?", a timer, a quick sum.
The app keeps working on every phone, tablet and computer on your Wi-Fi, and so do the TV remote and the volume limit.
What honestly needs a connection
Some things have to reach the outside world, and you should hear it from us rather than find out:
Alerts to phones. In the house the sirens sound and every screen shows the alarm, but the alerts to the family's phones and to your outside contacts need the internet.
Fresh weather. The last forecast stays on screen, marked with the time it was fetched, so you know how old it is.
Internet radio, podcasts, your music services and general-knowledge questions, as in any home.
Any device that only works through its maker's cloud. We point those out before we fit and suggest ones that work locally.
A power cut is a different question. With the power off, the hub and the router stop like anything else electrical, and the hub starts up again by itself when the power returns. If you want the house to keep going through a cut, an optional battery backup, around £100, keeps the hub and your router running.
Test any system in 10 minutes
Whatever you have now, or whatever you are thinking of buying, this is the honest test:
1Unplug the cable that brings the internet into your router, and leave the router switched on so the Wi-Fi stays up. Turn off mobile data on your phone so it cannot cheat.
2Open the app and switch a light on and off.
3Set the alarm, open a watched door, check the countdown starts, then disarm it with your PIN.
4Open the cameras and drag back over the last few minutes. They should be there.
5Ask for the lights off, or run a scene.
If any step fails, you have found the part of your home that lives in someone else's cloud.
How to get it
Every home we fit is built to pass that test from the first day. Tell us on WhatsApp what you have now and what you want to keep working when the broadband drops, and we will say what joins locally and what would need replacing, then put a fixed price in writing. Nothing a month after that.