"The internet is down" usually means something more specific
Fibre lines themselves often keep working through load shedding, because the exchange or POP feeding your suburb has its own backup power, sized to keep a few thousand homes connected at once. The signal gets to the pavement outside your house without a hiccup. What happens after that is entirely on you. The ONT bolted to your wall, the router on the shelf, the mesh pod covering your study — none of that has backup power unless you've put it there yourself. So the moment your area drops, all of it goes dark at the same time the lights do, and it looks exactly like the internet failing, when really the internet arrived and nothing was switched on to receive it.
I mention this because it changes what you're actually solving for. People spend money trying to fix a "bad connection" that was never the problem, when the real gap is a few metres of cable inside their own house.
What's worth keeping alive, and what isn't
There are really only two or three things worth putting on backup power for internet purposes. The ONT, which is the small box your fibre cable plugs into and converts to a signal your router understands. The router itself. And, if you work from a specific room, the one mesh pod covering that space. That's it. I've seen people try to run a desktop PC, a monitor, and a printer off the same small battery meant for networking gear, and it's flat within fifteen minutes, which defeats the purpose entirely.
What you actually want is a small UPS — a battery with an inverter and a couple of plug sockets, sitting between the wall and your equipment. The moment mains power drops, it switches over instantly. No gap, no reboot, no sitting there for two or three minutes while the router restarts and re-negotiates with the ISP, which is exactly what happens on a normal power cut and exactly what most people assume is unavoidable. It isn't.
Where people get this wrong, or overspend
The most common mistake is buying too much. Somebody sees a UPS rated to run a whole home office — PC, monitor, router, the lot — and pays for capacity they'll never use if all they actually needed was backup for the ONT and router. The second mistake runs the other way: buying the cheapest unit on the shelf without checking runtime, then being disappointed when it only lasts forty minutes on a day with two-hour outage slots. And the third one I see constantly — someone puts the router on backup power but forgets the mesh pod in the room they actually work from, so the internet is technically up, but the one part of the house that matters to them still has no signal.
Sizing it properly, without guessing
An ONT and router together typically draw well under 30 watts combined — genuinely not much. Even a modest, inexpensive UPS can carry that load for two to four hours, which covers a normal load shedding stage with room to spare. If you work from home daily or run a small business from the house, add the one mesh pod covering your workspace to the same unit rather than trying to back up the whole mesh network. You're covering the room you need, not the whole house, and the cost difference is significant. When you're choosing a unit, look past the "maximum runtime" printed on the box — that number is almost always measured against a tiny load nobody actually has. Check the runtime at the load you're actually going to put on it.
For most home offices, that means one small UPS carrying the ONT, the router and the pod in the room you work from. It's a modest outlay, especially next to the mobile data that gets burned tethering a phone every time the power goes. Stage 4 comes and goes, and you barely notice, because the room you actually need online stays online the whole time.
If you want a hand working out what your own setup draws and what size unit actually makes sense for it, get in touch. It's a five-minute conversation, not a sales pitch.