Quick answer: You need the internet for remote control from outside the home and for voice assistants, but not for everyday basics. With a Zigbee mesh system, wall switches, scenes and automations run locally through the hub, so lights and schedules keep working when your internet is down. Many Wi-Fi-only devices may stop responding.
What actually needs the internet in a smart home?
Remote access and voice assistants need the internet, while local control often does not. Which features stop depends on how your system is built.
A smart home has three layers. The first is the device itself, such as a smart switch or sensor. The second is the hub or gateway that devices talk to inside your home. The third is the cloud, the internet service that lets you control the home from outside and connects voice assistants.
Features that usually need the internet:
- Controlling your home from outside, such as at the office or on holiday
- Voice commands through Google Assistant or Amazon Alexa
- Push notifications to your phone when you are away
- Viewing CCTV remotely
Features that can run without the internet, if the system supports local control:
- Pressing smart wall switches
- Scheduled automations, such as lights on at 7pm
- Sensor-triggered automations, such as a motion sensor turning on a corridor light
Zigbee systems are built around local communication between devices and the hub, which is why they handle outages well.
What happens when the internet goes down?
With Zigbee, your home behaves almost normally inside the house. With cloud-dependent Wi-Fi devices, control can stop until the connection returns.
| Function | Zigbee system with local hub | Cloud-dependent Wi-Fi device |
|---|---|---|
| Wall switch press | Works | Usually works if it has a physical button |
| Scheduled automations | Work locally | May stop |
| Motion or door sensor automations | Work locally | May stop |
| App control while at home | Depends on the app and setup | Often stops |
| Control from outside the home | Stops until internet returns | Stops |
| Voice assistant | Stops | Stops |
The key point is that a well-designed home should never leave you unable to turn on a light. Physical switches matter, especially for children, elderly parents, guests and helpers who may not use the app.
When the internet comes back, cloud features such as remote access and voice control reconnect automatically in most systems.
What about power cuts?
A power cut affects every electrical device, smart or not. What matters is how devices behave when power returns and which items have their own battery.
When electricity is restored, mains-powered smart switches and the hub restart and reconnect to each other. Depending on the device settings, lights may return to off or to their previous state, which is worth configuring so lights do not all switch on in the middle of the night.
Battery-powered devices, such as many door and motion sensors, keep running during a power cut, but they cannot trigger mains-powered lights that have no power.
Smart door locks generally run on batteries, so they usually keep working during a blackout. Many models also provide backup ways to open the door, so ask your installer what your lock offers. Auto gates depend on the gate motor and whether it has a backup battery, which is separate from the smart control.
Your broadband router also needs power. If it goes off, remote access stops even if the rest of the house is fine.
How can you make your smart home more resilient?
Choose a system with local control for core functions, keep physical switches, and protect your router and hub. These steps cover most outage scenarios.
Practical steps:
- Use Zigbee for essentials. Put lights, curtains and key sensors on a local mesh rather than cloud-only Wi-Fi gadgets.
- Keep wall switches working. Everyone at home should be able to control lights without a phone.
- Place the hub and router centrally. Better coverage means fewer dropouts on upper floors.
- Consider a small UPS for your router and hub, so they ride through short power interruptions.
- Check Wi-Fi channels. Zigbee and Wi-Fi both use the 2.4 GHz band, so a good installer sets channels to reduce interference.
- Test before handover. Ask the installer to unplug the internet and show you which functions keep working.
These checks take little time during installation and save a lot of frustration later.
How DOMOS can help
DOMOS builds smart homes on a Zigbee mesh, so switches, scenes and automations keep working locally when the internet is down, with Wi-Fi devices added where they fit. Everything sits in one app and works with Google Assistant and Amazon Alexa when you are online. With more than 10 years in home automation, we serve homes across KL and Selangor from our base in Semenyih. Packages range from RM6,980 to RM39,980 including supply, installation, app setup and handover. See our smart home price guide or WhatsApp 016-530 2629 for a free site visit.