Best battery backup for a WiFi router

The short answer

For a modem and router, a small UPS such as the APC Back-UPS 600VA (BE600M1) or CyberPower CP685AVRG covers short outages and protects gear from surges. For outages measured in hours or days, a portable power station with a UPS-style switchover does better. Add up your devices' watts and divide your battery's usable watt-hours by that total.

A home internet connection usually runs through two or three boxes: the modem or fiber optical network terminal (ONT), the WiFi router, and sometimes a mesh node or a VoIP phone adapter. All of them stop when the outlet does. A battery backup keeps them up through brief flickers, which also spares you the several-minute reboot that follows each one.

At a glance

UPS picks

The two UPS units most people should start with have full write-ups: read the full BE600M1 review and read the full CP685AVRG review.

No. 1UPS

APC Back-UPS 600VA (BE600M1)

Best for: A compact, low-cost UPS for a modem and router on a shelf

• 600 VA / 330 W
• 7 outlets: 5 battery-backed, 2 surge-only
• 1 USB-A charging port
• 12 V lead-acid battery; about 10 hrs typical recharge
• 6 ms typical transfer time; stepped sine wave output
• Replacement battery: APC APCRBC154; 490 J surge rating
• 7.69 lb; 3-year UPS warranty, 1-year battery warranty

Tradeoffs

• · Stepped (not pure) sine wave output, which is fine for most network gear
• · One small lead-acid battery, so expect a few hours at most for a modem and router

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 2UPS

CyberPower CP685AVRG AVR UPS

Best for: A small line-interactive UPS with voltage regulation for brownout-prone areas

• 685 VA / 390 W; line-interactive with automatic voltage regulation
• 8 outlets: 4 battery-backed, 4 surge-only
• 12 V / 7 Ah sealed lead-acid battery, user replaceable
• Maker runtime: 11 min at half load, 2 min at full load; 8 hrs typical recharge
• 4 ms typical transfer time; replacement battery RB1270B or RB1280, by serial number
• 11.62 lb; 3-year warranty including batteries

Tradeoffs

• · Simulated sine wave output on battery
• · Only four battery-backed outlets

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 3UPS

APC Back-UPS Pro 1500S (BR1500MS2)

Best for: Longer runtime for a modem, router, ONT and a mesh node, with a pure sine wave

• 1,500 VA / 900 W; line-interactive, sine wave output, AVR
• 8 ms typical transfer time; replacement battery APC APCRBC163
• 10 outlets: 6 battery-backed, 4 surge-only
• USB-A and USB-C charging ports; LCD status console
• Lead-acid battery, user replaceable; about 16 hrs typical recharge
• 27.6 lb; 3-year UPS warranty, 1-year battery warranty

Tradeoffs

• · Heavy and large for a network shelf
• · 16-hour recharge means a second outage soon after the first finds it partly charged

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 4UPS

CyberPower CP1500PFCLCD PFC Sinewave UPS

Best for: Two batteries' worth of runtime for network gear plus a desktop computer

• 1,500 VA / 1,000 W; line-interactive, sine wave output
• 12 outlets: 6 battery-backed, 6 surge-only
• Two 12 V / 9 Ah sealed lead-acid batteries, user replaceable
• Maker runtime: 10 min at half load, 2.5 min at full load; 8 hrs typical recharge
• 4 ms typical transfer time; replacement battery RB1290X2 or RB1280X2B, by serial number
• USB-A and USB-C charge ports; tilting LCD
• 24.9 lb; 3-year warranty including batteries

Tradeoffs

• · Overkill if you only need to run a modem and router
• · About 25 lb

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

Power station picks for longer outages

No.	Model	Capacity	Cont. / surge	Chemistry / fuel	Weight
01	Small and lightEcoFlow RIVER 3 PlusKeeping a modem and router online through an evening or a nightFull specs, strengths and tradeoffsCheck price on Amazon	286 Wh	600 / 1,200 W	LiFePO4 (LFP)	10.4 lb
02	All-day backupAnker SOLIX C1000Running the internet for a day or more while also powering a fridge or lightsFull specs, strengths and tradeoffsCheck price on Amazon	1,056 Wh	1,800 / 2,400 W	LiFePO4	28.44 lb

• 01

  Small and lightEcoFlow RIVER 3 Plus
  

  Keeping a modem and router online through an evening or a night

  Capacity

  286 Wh

  Cont./surge

  600 / 1,200 W

  Chem./fuel

  LiFePO4 (LFP)

  Weight

  10.4 lb

  Full specs, strengths and tradeoffs
  Check price on Amazon
• 02

  All-day backupAnker SOLIX C1000
  

  Running the internet for a day or more while also powering a fridge or lights

  Capacity

  1,056 Wh

  Cont./surge

  1,800 / 2,400 W

  Chem./fuel

  LiFePO4

  Weight

  28.44 lb

  Full specs, strengths and tradeoffs
  Check price on Amazon

No. 1Small and light

EcoFlow RIVER 3 Plus

Best for: Keeping a modem and router online through an evening or a night

At 286 Wh and 10.4 lb, the RIVER 3 Plus holds several times the energy of a small lead-acid UPS. EcoFlow lists a sub-10 ms UPS switchover, so it can sit between the wall and your network gear full time.

Strengths

• Under 10 ms switchover per EcoFlow
• LiFePO4 rated for 3,000 cycles to 80%
• Expands to 858 Wh

Tradeoffs

• Only three AC outlets
• Small for anything beyond network gear and phones

• Note: X-Boost runs some higher-watt resistive devices at reduced power (up to 1,200 W per EcoFlow).

Capacity	286 Wh
AC output	600 W continuous / 1,200 W surge
Battery	LiFePO4 (LFP)
Weight	10.4 lb
Max solar input	220 W
Rated cycles	3,000 cycles to 80%
AC outlets	3
UPS switchover	<10 ms
Expansion	Up to 858 Wh with an EcoFlow extra battery

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

No. 2All-day backup

Anker SOLIX C1000

Best for: Running the internet for a day or more while also powering a fridge or lights

1,056 Wh is enough to run a typical modem and router for a day or more on our math below, with capacity left for phones and lights. Anker lists a switchover under 20 ms.

Strengths

• Six AC outlets
• Expandable to 2,112 Wh
• Solar input up to 600 W

Tradeoffs

• About 28 lb
• Its sub-20 ms switchover is slower than a standby UPS; most routers ride through it, but check yours

• Note: A newer C1000 Gen 2 has different specs. Make sure the listing matches the model you want.

Capacity	1,056 Wh
AC output	1,800 W continuous / 2,400 W surge
Battery	LiFePO4
Weight	28.44 lb
Max solar input	600 W
Rated cycles	3,000 cycles to 80%+
AC outlets	6
Expansion	Up to 2,112 Wh with the matching expansion battery

Check price on AmazonRead the full reviewSpecs: manufacturer page, checked Nov 1, 2026

Battery backup for modem and router: the runtime math

Every power adapter lists its output on the label, for example 12 V and 1.5 A. Multiply to get the maximum watts: 12 x 1.5 = 18 W. That figure is a ceiling; the device usually draws less. Add the ceilings for each box you need, then do the division.

Lead-acid UPS batteries are smaller and deliver a lower share of their rating. The CyberPower CP685AVRG has one 12 V, 7 Ah battery, which is 84 Wh nominal. The CP1500PFCLCD has two 12 V, 9 Ah batteries, 216 Wh nominal. CyberPower quotes runtime at half and full load (11 and 2 minutes for the CP685AVRG), which tells you little about a 30 W load. Use the maker's runtime chart or CyberPower's online runtime calculator for your actual watts.

If you want a full-home estimate that includes the router, a fridge and medical devices, the BackupPowerAI sizing quiz adds them up.

Battery backup for internet: what the box cannot fix

Your router can stay on and still have nothing to connect to. Cable and DSL service runs through powered equipment outside your home, and the cell towers that carry 5G home internet need power too. Any of it can go down in a wide or long outage. A battery backup for internet protects you from the outage at your house, not from one across your provider's network.

If your home phone runs over fiber, cable or VoIP, it also needs power. The FCC requires providers of these non-line-powered home voice services to offer for sale at least one backup power option with 8 hours of standby power, and since February 13, 2019, an option with at least 24 hours. Buying it is your choice. Providers must also disclose at the point of sale and each year how long backup lasts and how to test it.

Choosing between a UPS and a power station

• Switchover speed: a UPS is designed to switch in milliseconds. The APC BE600M1 lists 6 ms typical and 10 ms maximum. Some power stations list UPS switchover times under 10 or 20 ms; others list none.
• Capacity: a lead-acid UPS stores tens to a couple hundred watt-hours. A small power station stores roughly 300 Wh, a mid-size one about 1,000 Wh.
• Battery life: APC lists 3 to 5 years of battery life for the BE600M1. The LiFePO4 stations here are rated for thousands of cycles.
• Waveform: pure sine wave output (BR1500MS2, CP1500PFCLCD, power stations) suits any device. Stepped or simulated sine wave output (BE600M1, CP685AVRG on battery) is generally fine for network adapters.
• Recharge: APC lists 10 hours to recharge the BE600M1 and 16 hours for the BR1500MS2. A power station can refill from a car or solar panels during a long outage.

Setup tips

1. 01Plug the modem or ONT, router and any VoIP adapter into the battery-backed outlets, not the surge-only ones. Label them.
2. 02Leave printers, monitors and speakers on surge-only outlets so they do not drain the battery.
3. 03If your fiber ONT has its own provider battery unit, keep it; a UPS upstream extends it.
4. 04Pull the plug once a season to confirm everything stays up and to see how the UPS reports remaining time.
5. 05Keep phones charged too. Our phone charging guide and radios and power banks kit cover that side.