Work out what you actually need to keep alive
Start by listing the equipment that must stay powered for the internet to work, then measure or look up what each item draws. A typical 4G or 5G router draws somewhere in the region of ten to twenty-five watts. A mesh node draws less. An eight-port switch is usually under ten watts unless it is supplying power over Ethernet.
Add them up and the total for a household network is frequently under fifty watts. That is a very small load, which is why keeping the internet running is far cheaper than keeping a fridge or an air conditioner running, and why a full inverter installation is usually unnecessary if the internet is all you need.
Then decide what else must stay on. A laptop has its own battery and needs nothing. A desktop computer, a satellite terminal, a network video recorder or a PoE camera system each add substantially to the load and change the sizing completely.
- Router — typically 10 to 25 W.
- Mesh node or access point — typically 5 to 12 W each.
- Unmanaged 8-port switch — typically under 10 W.
- PoE switch with cameras — considerably more; size against the actual camera count.
- Satellite terminal — significantly higher than a mobile router; check the specification.
Choosing the right kind of backup
A mini DC UPS designed for routers is the neatest answer for a small network. It supplies the router's DC voltage directly rather than converting to mains and back, which is more efficient, silent and far cheaper than a conventional UPS for the same runtime.
A conventional mains UPS makes sense when you need to back up several devices, or equipment that does not take a simple DC input. Size it by watts and required runtime rather than by the VA figure on the box, because VA ratings overstate what you will get at a small real load.
A portable power station or an inverter with a lithium battery is the right choice when you need to carry several hundred watts, or run a satellite terminal, or keep a desktop and a recorder alive as well. These cost more but cover the whole working setup rather than just the connection.
Technician’s tip
Size for the longest outage you realistically expect, then add a margin. Batteries deliver less than their rated capacity as they age, and a backup that just barely covered an outage when new will fall short in two years.
Protect the equipment as well as the uptime
Power returning after an outage is often worse for equipment than the outage itself. Surges and voltage swings on restoration damage routers, switches and recorders, and a modest surge protector on both the mains and any external antenna or Ethernet run is inexpensive insurance.
If your supply is genuinely unstable, a voltage regulator or a UPS with automatic voltage regulation is worth the additional cost. Consistently low voltage is more damaging to electronics over time than a clean outage.
Never run network equipment directly from a generator output without conditioning. Generator power can be electrically noisy, particularly at start-up and under changing load.
Remember the rest of the chain
Backing up your router only helps if the connection itself survives. A SIM-based mobile router is well placed here, because the mast has its own backup arrangements and there is no last-mile equipment in your street to fail.
If your connection depends on equipment elsewhere on your premises — a fibre terminal, a building distribution unit or a shared point in a compound — that equipment needs backup too, or your fully powered router will sit there with no service behind it.
This is also a strong argument for keeping a charged MiFi with a data bundle on a different network. It is the cheapest possible diverse fallback and it needs no installation at all.
Business continuity, briefly
For a business, the question is not whether the internet goes down but how long the business can operate without it. Work that out honestly — a shop with a card terminal may lose revenue within minutes, while an office may cope for an hour.
Layer the protection accordingly: power backup for the equipment, a second network on a different operator for the connection, and a router capable of failing over between the two automatically. Manual failover that depends on someone noticing and swapping a cable is not continuity, it is hope.
Test the arrangement deliberately. Pull the mains and confirm everything keeps running for as long as you expect, then pull the primary SIM and confirm failover happens. An untested backup is an assumption, and outages have a reliable habit of exposing assumptions.