You do not need a protocol strategy to put a timer on a geyser.
You need 2.4 GHz to reach the cupboard. Everything else is extra.
The blunt version
| Protocol | Use it for | Do not use it for |
|---|---|---|
| Wi‑Fi | First relays, geyser, gate, a handful of plugs | Fifty sensors on a tired fibre router |
| Zigbee | Battery sensors, buttons, a growing mesh | “I bought a dongle on day one and nothing else” |
| Matter | Future-proofing on new switches when the device is actually Matter | Assuming it replaces Home Assistant |
Start Wi‑Fi. Add Zigbee when the sensor count grows. Let Matter hitch a ride later. That matches how we tell people to start.
Wi‑Fi — the SA default
Almost every first Sonoff and a lot of Shelly units are Wi‑Fi. The app works. The electrician understands it. Stock is on the shelf.
It fails when:
- The router is 5 GHz-only for guests and 2.4 GHz is an afterthought
- The geyser is two brick walls and a roof void away
- The gate motor is a Faraday cage — see gates
- You put thirty devices on a free ISP router from 2018
Fixes that work: 2.4 GHz enabled, a mesh node that is not a mystery special, ethernet to the Green.
Wi‑Fi devices also mean each one is another client. Fine at five. Rude at fifty.
Zigbee — when sensors multiply
Zigbee is a mesh between devices. Mains-powered bulbs and plugs can extend it. Battery sensors ride along.
Good for: door contacts, motion, buttons, temperature probes that should not eat Wi‑Fi.
You need a coordinator: a dongle on Home Assistant, or a brand hub. The Green does not include Zigbee until you add a stick. That is normal. Hardware choices.
Do not mix random cheap Zigbee with no plan and then declare the protocol broken. One coordinator. Current devices. A couple of always-on routers in the mesh.
Matter — useful, not a personality
Matter is a common language. Some new Sonoff wall switches speak it. That helps if you want Apple / Google / Alexa / Home Assistant to see the same switch without a brand prison.
It does not:
- Fix a dead Wi‑Fi cupboard
- Replace a local hub if you want serious automations
- Make a 2019 Basic R2 into something it is not
Buy Matter when the switch in front of you is Matter and the price is sane. Do not rip out working Wi‑Fi relays for a logo.
Load shedding does not care about the protocol
No power, no mesh, no Wi‑Fi, no Matter. Battery Zigbee sensors still *exist*, but they cannot switch a dead geyser. Put the hub and the router on backup. Protocol debates after that.
What we spec
- House with under ~10 devices: Wi‑Fi, done
- House collecting sensors: add Zigbee to Home Assistant
- New wall switches on a refresh: consider Matter models if stocked
- Mixed Sonoff + Shelly: the brand post, then one hub
Browse gateways and sensors only after the first circuit works.
FAQ
Should I wait for Matter before I start? No. Heat water on a schedule this month.
Is Zigbee more reliable than Wi‑Fi? A good Zigbee mesh is very good for sensors. A bad one is worse than three honest Wi‑Fi relays. Installation quality beats the acronym.
Can I mix all three? Yes, in Home Assistant. That is the point of the hub.
Does fibre vs LTE change this? The last mile does not. The router in the lounge does.
