Best 4G/5G Backup Internet Australia 2026:
5 Picks $104 to $579 for When the NBN Drops

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Why the fixed line drops, and what a backup covers

Most NBN dropouts I hear about at the counter come down to one of three things. On fibre to the node, the last stretch to the house is old copper, and copper in a pit that fills after a storm gets noisy, drops out and comes back as the weather changes. The second is equipment at the house: modem power supplies and the small plug packs that run the NBN box fail more often than people expect, usually after a few summers in a hot cupboard. The third is the network itself, which you can't do anything about except wait.

A 4G or 5G router with a SIM in it covers all three, because it doesn't use the fixed line at all. It talks to the nearest mobile tower and shares that connection over Wi-Fi like any other router. For a household that works from home, runs a small business, or has someone who relies on a video call to keep a business running or catch up with the grandkids, that's the difference between a day lost and a slightly slower day.

What it won't cover is a full blackout on its own. The router needs power, and so does the mobile tower. Towers usually have battery backup for some hours, but a long, widespread outage can take them down too. I'll come back to power further down, because it's the part people forget until the first time they need the thing.

4G or 5G: what you'll actually get at your address

Start with coverage, not with the router. Every carrier publishes a coverage map, and the useful thing to check is the outdoor and indoor coverage at your actual address, not the suburb. If the map shows 5G at your place, a 5G router can be properly quick. If it shows 4G only, a 4G router does the same job for a lot less, and for a backup connection that mostly carries video calls, email and a bit of streaming, 4G is usually plenty.

Indoors versus outdoors matters more than people think. Brick veneer, foil-backed insulation and tinted low-E glass can knock a 4G signal down hard, which is why a phone that shows full bars in the yard can struggle in the back bedroom. Before you buy anything, stand where the router would go and run a speed test on your phone using the same carrier you plan to use for the SIM. That one test tells you more than any brochure.

The 4G routers in this guide quote up to 150 Mbps download, which is the ceiling of the radio, not what you'll see. In my experience a good indoor 4G signal gives somewhere in the tens of megabits, and a weak one gives a few. That's still enough for a video call or two. The 5G units quote multi-gigabit figures that are lab numbers; real 5G is often a few hundred megabits on a good day, which beats a lot of NBN plans.

Two things to check before you buy. First, the 3G networks are gone in Australia, so anything you buy has to be 4G or 5G, which all of these are. Second, the low 700 MHz band (band 28) is the one that carries furthest and gets through walls best, and it matters a lot in regional areas and at the fringe of town. None of the listings here state their supported bands, so check the manufacturer's spec sheet for band 28 before you order, especially if you're out of town.

The data cost maths for an outage

A backup connection is only as useful as the data on the SIM. Rough figures are fine for planning. A one-on-one video call uses somewhere around half a gigabyte to a gigabyte an hour depending on the app and quality, a group call in HD can use more, and HD streaming runs at roughly 3 GB an hour. Background stuff is the one that catches people out: phone and computer updates, cloud photo backups and game downloads all start the moment they see a fast connection, and they don't know it's a mobile SIM.

So here's a worked example. Two people working from home with four hours of calls each is maybe 6 to 8 GB a day. Add an evening of streaming and you're past 10 GB. A three-day outage is 30 GB or more, before any updates sneak through. That's why I'd set up a backup SIM with a decent chunk of data and a long expiry, and turn off automatic updates and cloud sync while you're running on it. Most phones and computers let you mark a Wi-Fi network as metered, which does most of that in one switch.

For the plan itself, look at data-only SIMs with long-expiry prepaid packs, or adding a data SIM to an existing mobile account, which some carriers will do for a small monthly fee. Check the current plans on the day; they change constantly. The point is to have something already active in the router, because a SIM that's expired or still in the packet is no use at 9am on the morning the line goes down. If you're on the fringe of town or further out, check whether the plan runs on the carrier's full network, because some resold plans may not get every band or the newest 5G sites.

Failover: automatic, manual, and what the listings actually say

Failover is the router noticing the fixed line has dropped and switching to the mobile connection on its own. It's the setup everyone wants, and it's the one most listings are vaguest about. None of the five listings here say outright that they do automatic failover between the NBN and the SIM. Two of them (the TP-Link MR402 and the Mercusys MB520-5G) have a port that can take a wired connection instead of the SIM, which tells you they can run on either, but not that they'll switch between them by themselves. Check the manufacturer's manual for a backup or failover setting before you count on it.

• Manual swap: the mobile router sits in a drawer, charged and with an active SIM. When the line drops, you plug it in or turn the hotspot on and connect to it. It's the simplest setup and it works, it just needs someone home.
• Second network: the mobile router runs all the time on its own Wi-Fi name. When the NBN drops, devices that matter get switched over by hand.
• Dual-WAN: your main router supports a backup internet port, and the mobile router plugs into it. The main router handles the switch. This is the proper automatic setup, but it depends on your main router having the feature.

If you're buying a new main router anyway, the home Wi-Fi router guide is worth a look for models with a WAN backup setting. For a small office where nobody can be home to swap things over, dual-WAN is the setup I'd push for. For most households, a manual swap that takes two minutes is perfectly fine, and it's a lot less to go wrong. Whatever you choose, give the backup Wi-Fi a different name from the main one. If both networks share a name, devices hop between them unpredictably, and you'll never be sure which connection a call is running on.

Antennas, outdoor units and the booster you shouldn't buy

If the signal inside is weak, the fix is usually height and a clear line to the tower, not a bigger number on an antenna box. The catch with a roof antenna is the cable. Coax loses signal along its length, and the thin cable that comes with a lot of antenna kits can throw away a good part of what the antenna gained over a few metres. That's why outdoor routers like the Mercusys MB118-4G exist: the radio goes up on the pole or wall with the antennas, and a single Ethernet cable carries both data and power (PoE) back inside, with no signal lost on the way down.

Indoor routers with detachable antennas, like the TP-Link MR402, let you swap in a better antenna or run a short lead to a window. The listings don't state the connector type, so check it before ordering an antenna, and keep any lead as short as you can. For a short-term fix, try the router in a few spots first. A metre higher, or on the side of the house facing the tower, often makes more difference than any accessory.

The thing not to buy is a mobile signal booster or repeater. They're sold online and they look like an easy fix, but in Australia it's illegal to use one without the carrier's permission, and the ACMA does chase them down because a badly behaved booster can interfere with the network for everyone nearby. An external antenna plugged into your own router is fine. A box that rebroadcasts the carrier's signal isn't.

Keeping it powered when the power's out too

A mobile router is a low-power device. Most draw well under 20 W, and the adapter's rating on the label tells you the most it can pull. That makes them easy to keep running. The portable hotspots in this guide have their own batteries, and the M7005's listing quotes up to 12 hours. For the mains-powered routers, a small UPS for the router and modem will keep them going through a short blackout. Check the NBN side too. On fibre to the premises the connection box needs mains power, and on fibre to the node the node in the street needs power as well, with limited battery backup, so in a long blackout the fixed line is usually gone whatever you do at home.

For longer outages, a power station does the job. Rough maths: a router drawing 12 W from a 500 Wh power station runs for around 30 hours once you allow for inverter losses, and longer if the power station has a DC or USB-C output the router can use directly, since you skip the inverter altogether. Our portable power station picks go through sizing in more detail.

Remember the plug pack too. A lot of router failures we see are the power supply, not the router, and a no-name replacement from a market stall is how people end up with a fried board. The guide to bad chargers explains why, and the short version is to use the supplied adapter or a proper replacement with the same voltage, polarity and connector.

Setting it up so it works on the day you need it

A backup that hasn't been tested isn't a backup. Once a month, unplug the NBN for ten minutes and run off the mobile router: check it connects, check the speed, check the devices that matter can find it. It's also when you'll notice a SIM that's been suspended for not being used, which some prepaid plans do after a few months of no activity, or a router that wants a firmware update.

Write the Wi-Fi name and password on a label on the router itself, and keep a note of the SIM's number and carrier with it. The day you need the backup is usually a stressful day, and nobody remembers which drawer the login is in. If you've set a SIM PIN, note that somewhere safe too, because three wrong guesses locks the SIM until you get the PUK code from the carrier. Keep the backup SIM on a different carrier from your phones if you can. A fault that takes out one carrier won't take out the other, and you'll still have the phones as a third option.

If the router, the NBN box or a home office computer starts misbehaving and you can't tell which bit has failed, that's the kind of thing we sort out at the computer repair side of the shop. And if it's a phone's hotspot that's playing up when you need it as the backup, bring it into our Erina workshop; a phone that drops its hotspot under load is often a battery or heat problem rather than the network.

The 5 picks, $104 to $579

Prices are Amazon AU at time of writing (2 October 2026) and move week to week. Ranks are Amazon AU category sales ranks, checked the same day.

Side-by-side comparison

What we see fail at the bench: mobile routers and hotspots

Mobile routers are simple boxes, and they fail in simple ways. When one stops connecting, it's rarely the radio. It's usually the power, the SIM contacts, or heat from being stuck in a cupboard or on a sunny windowsill. These are the three we see most, and all of them are easier to prevent than to fix. Most of them can be sorted on the counter in a few minutes.

Decision tree: which one should you actually buy?

• Want the simplest backup you can switch on in a blackout? → The TP-Link M7005 at $110. It has its own battery and fits in a drawer.
• Signal inside the house is weak? → The Mercusys MB118-4G at $104 mounts outside and runs data and power down one Ethernet cable.
• Want a proper router to run the whole house off a SIM? → The TP-Link Archer MR402 at $153, with dual-band Wi-Fi and detachable antennas.
• Got real 5G at your address and want a home phone that survives an outage? → The Mercusys MB520-5G at $411, with Wi-Fi 6, a 2.5 Gbps port and a VoLTE phone port.
• Work on the road or need to switch carriers when one goes down? → The Netgear Nighthawk M7 at $579, with one SIM plus up to 8 eSIMs.
• Router dead, hotspot swelling or phone hotspot dropping out? → Bring it to our Erina workshop and I'll tell you what's failed and whether it's worth fixing before anything's done.

Frequently asked questions

Can I use 4G as a backup for the NBN?

Yes. A 4G router with an active SIM gives you a separate connection that doesn't rely on the fixed line at all, so it keeps working when the NBN drops. For most households it's plenty for video calls, email and some streaming. The two things to sort out first are coverage at your actual address, using the carrier's map, and a SIM with enough data and a long enough expiry that it's still active on the day you need it.

Does a 4G router switch over automatically when the NBN goes down?

Only if it's set up for it. Automatic switching needs a router with a failover or backup WAN setting, either in the mobile router itself or in your main router with the mobile router plugged into its backup port. None of the listings in this guide confirm automatic failover outright, so check the manufacturer's manual. A manual swap, where you turn the backup on and connect to it, works fine for most homes.

How much data do I need for a backup internet plan?

Plan on roughly 2 to 5 GB a day for one person working from home with video calls, and more if anyone's streaming. HD streaming runs at roughly 3 GB an hour. A three-day outage for a busy household can pass 30 GB. Turn off automatic updates and cloud backups while you're on the backup, or mark the network as metered, because those can burn through a data pack in an hour.

Will a 4G router work during a blackout?

It will if it has power and the mobile tower is still running. Pocket hotspots have their own batteries, and mains routers can run off a small UPS or a power station, since most draw well under 20 W. Mobile towers usually have battery backup for some hours, but a long, widespread blackout can take them down too, so a mobile router covers most outages but not every one. Test it once with the mains off, so you know how long things actually last.

Are mobile signal boosters legal in Australia?

Not without the carrier's permission. Mobile repeaters and boosters that rebroadcast the network's signal are illegal to use in Australia unless the carrier has authorised them, and the ACMA does act on them because they can interfere with the network for other people. An external antenna connected to your own 4G or 5G router is a different thing and is fine. If indoor signal is weak, an outdoor router or a better antenna is the legal way to fix it.

Is 5G worth it over 4G for a backup?

Only if you have solid 5G coverage at your address and you'll use the speed. For a backup that mostly carries calls and email, 4G is usually enough and the routers cost a lot less. 5G makes sense if the backup needs to carry a whole busy household, or if you might use it as your main connection because the fixed line at your place is poor. Check the coverage map at your address before deciding.

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