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ASUS RT AC51U Review | 77 Data compared

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  • Avg. price in UK: ~£35
  • Avg. price in US: ~$40
  • Wi-Fi version: Wi-Fi 5 (802.11ac)
  • Wi-Fi speed: 733 Mbps
  • LAN port speeds: 100 Mbps
  • Wireless coverage: ?

ASUS RT AC51U review. Compare 77 technical specifications and user reviews to see how it ranks among routers and if it is worth buying.

6.7

Overall score

What it is: An overall evaluation of the router's quality, based on technical analyses and user reviews.

When it matters: When you need a quick reference to identify the best routers on the market.

Score components:

90.0%

6.5

Technical Score

10.0%

8.8

User score

Good
6.5

Technical Score

What it is: An assessment of the router's technical performance, covering key areas such as Wi-Fi performance, wired connectivity, security, software features, coverage, and design.

When it matters: When you want to compare routers based on technical performance and available features.

Score components:

26.0%

4.5

Wireless

20.0%

5.6

Ports

18.0%

9.5

Networking

14.0%

9.1

Security

12.0%

4.0

Hardware

10.0%

7.5

Management

Good
8.8

User score

What it is: A rating that combines user reviews and the total number of reviews received by the router.

When it matters: When you want to know how a router performs in daily use and how reliable it is for speed, coverage, and stability according to user feedback.

Score components:

70.0%

8.4

User reviews

30.0%

10

Popularity

User score:
United Kingdom
amazon
4.2
(4779)
amazon
4.0
(384)
amazon
4.0
(154)
United States
Amazon_logo.png
4.3
(869)
Amazon_logo.png
4.0
(372)
Amazon_logo.png
4.0
(154)
Amazon_logo.png
3.1
(10)

(Reviews last updated: May 2026)

Excellent
  • 4.6
    Gaming

    Score components:

    33.0%

    2.0

    Wi-Fi speed

    28.0%

    7.0

    CPU clock speed

    22.0%

    1.9

    RAM capacity

    17.0%

    9.0

    Maximum connected devices

  • 5.4
    Travel

    Score components:

    40.0%

    9.7

    Weight

    30.0%

    2.0

    Wi-Fi speed

    20.0%

    4.0

    Cellular modem type

    10.0%

    1.0

    SIM slot

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Best prices in UK

Best rankings

?

Available: ranking among products currently available (including other versions of this product).
All: ranking among all products in the database.

Verdict

The ASUS RT-AC51U is an AC750 dual-band Wi-Fi 5 router that delivers combined wireless speeds of up to 733 Mbps, with 300 Mbps on the 2.4 GHz band and 433 Mbps on the 5 GHz band. Its primary characteristics include a versatile USB 2.0 port for printer sharing, storage, or 3G/4G dongle support, alongside two high-gain external antennas that enhance coverage by up to 150%. Main pros include an extremely simple 30-second setup via the ASUSWRT dashboard, VPN server capabilities, and advanced parental controls. However, notable cons include its limitation to Fast Ethernet (10/100 Mbps) WAN and LAN ports, which caps wired internet speeds at 100 Mbps regardless of higher wireless ratings, and the lack of MU-MIMO technology for managing multiple high-demand devices simultaneously.

Technical Specifications of router ASUS RT AC51U

Technical Score

What it is: An assessment of the router's technical performance, covering key areas such as Wi-Fi performance, wired connectivity, security, software features, coverage, and design.

When it matters: When you want to compare routers based on technical performance and available features.

Score components:

26.0%

4.5

Wireless

20.0%

5.6

Ports

18.0%

9.5

Networking

14.0%

9.1

Security

12.0%

4.0

Hardware

10.0%

7.5

Management

6.5
ASUS RT AC51U has a technical score of 6.5 points, which is lower than that of 53.7% of products in this category.
User score

What it is: A rating that combines user reviews and the total number of reviews received by the router.

When it matters: When you want to know how a router performs in daily use and how reliable it is for speed, coverage, and stability according to user feedback.

Score components:

70.0%

8.4

User reviews

30.0%

10

Popularity

User score:
United Kingdom
amazon
4.2
(4779)
amazon
4.0
(384)
amazon
4.0
(154)
United States
Amazon_logo.png
4.3
(869)
Amazon_logo.png
4.0
(372)
Amazon_logo.png
4.0
(154)
Amazon_logo.png
3.1
(10)

(Reviews last updated: May 2026)

8.8
ASUS RT AC51U has a user score of 8.85 points, which is higher than that of 73.3% of products in this category.
Popularity
What it is: An indicator based on the number of reviews received by the router.
When it matters: When you prefer to choose a router reviewed and selected by many other buyers.
10
ASUS RT AC51U has a popularity of 10 points, which is higher than 63.5% of products in this category.
Ratio quality/price

What it is: An indicator that combines the router's overall rating with its cost.

When it matters: When you are looking for a router with a good balance between network performance, features, and price.

Score components:

60.0%

6.7

Overall score

40.0%

10

Price

7.7
ASUS RT AC51U has a quality-to-price ratio of 7.7 points, which is higher than 53.4% of products in this category.
Brand name
What it is: The manufacturer or brand of the product.
When it matters: When you prefer a specific ecosystem, support network, or design philosophy.

Importance: MEDIUM

Asus
Wi-Fi version
What it is: Identifies the Wi-Fi generation the router supports, such as Wi-Fi 5, 6, 6E, or 7.
When it matters: When newer phones, laptops, and consoles need the latest Wi-Fi efficiency and speed features.

Importance: HIGH

Good value: Wi-Fi 6 (802.11ax)

Wi-Fi 5 (802.11ac)
ASUS RT AC51U uses Wi-Fi Wi-Fi 5 (802.11ac), which is more advanced than 39.4% of routers and equal to 25.4% of routers.
Wi-Fi bands
What it is: Lists which wireless frequency bands the router can use, such as 2.4 GHz, 5 GHz, or 6 GHz.
When it matters: When you need to balance range, speed, and congestion across different types of client devices.

Importance: HIGH

Good value: 2.4 GHz + 5 GHz

2.4 GHz + 5 GHz
ASUS RT AC51U supports 2.4 GHz + 5 GHz Wi-Fi bands, which are more versatile than 25% of routers and equal to 67.9% of routers.
Wi-Fi speed
What it is: The advertised maximum wireless throughput rating of the router under supported conditions.
When it matters: When several users stream, download, and game at once and you want more wireless headroom.

Importance: HIGH

Good value: >2700 Mbps

733 Mbps
ASUS RT AC51U delivers 733 Mbps Wi-Fi speed, which is lower than 66.3% of routers.
Channel widths supported
What it is: Lists the Wi-Fi channel widths the router can use, such as 20, 40, 80, or 160 MHz.
When it matters: When you want the option to trade peak speed against stability in crowded wireless environments.

Importance: MEDIUM

Good value: 20 MHz + 40 MHz + 80 MHz

20 MHz + 40 MHz + 80 MHz
ASUS RT AC51U supports 20 MHz + 40 MHz + 80 MHz channel width options, which is more than 40.4% of routers and the same as 32.1% of routers.
Show more
Wi-Fi security protocols
What it is: Lists the wireless security standards the router supports, such as WPA2 or WPA3.
When it matters: When you want stronger wireless protection without locking out older devices that still need compatibility.

Importance: HIGH

WPA2, WPA, WEP, WPS
ASUS RT AC51U supports WPA2, WPA, WEP, WPS Wi-Fi security protocols, which are less advanced than 67.3% of routers and equal to 11.6% of routers.
DoS protection
What it is: Provides defenses intended to reduce the impact of denial-of-service traffic against the router or network.
When it matters: When exposed services or remote access make resilience against traffic floods more important.

Importance: HIGH

yes
ASUS RT AC51U includes DoS protection. 11% of routers include DoS protection.
SPI intrusion protection
What it is: Uses stateful packet inspection to track sessions and block suspicious unsolicited traffic more accurately.
When it matters: When the router needs a stronger first line of filtering on an internet-facing connection.

Importance: HIGH

yes
ASUS RT AC51U includes SPI-based intrusion protection. 3.6% of routers include SPI-based intrusion protection.
MAC address filtering
What it is: Lets the router allow or block devices based on their MAC addresses.
When it matters: When you want an extra device-level access rule beyond passwords and network names.

Importance: MEDIUM

yes
ASUS RT AC51U supports MAC address filtering. 1% of routers include MAC address filtering.
URL filter
What it is: Allows the router to block or allow access based on website addresses or domain rules.
When it matters: When you need to restrict specific sites for children, guests, or work-policy reasons.

Importance: MEDIUM

yes
ASUS RT AC51U supports URL filtering. 1.8% of routers include URL filtering.
Show more
IPv6 support
What it is: Support for the newer IPv6 internet addressing standard alongside the older IPv4 system.
When it matters: When your internet provider or network already uses IPv6, or you want the router to stay compatible as IPv6 use becomes more common.

Importance: HIGH

yes
ASUS RT AC51U supports IPv6. 10.9% of routers are IPv6-ready.
Dynamic routing
What it is: Supports routing protocols or dynamic route updates instead of relying only on static route entries.
When it matters: When the router sits in a more complex network with changing paths between multiple subnets.

Importance: MEDIUM

yes
ASUS RT AC51U supports dynamic routing. 46.8% of routers support dynamic routing.
Inter-VLAN routing
What it is: Allows the router to pass traffic between separate VLANs under controlled rules.
When it matters: When you need segmented networks to communicate selectively instead of staying fully isolated.

Importance: MEDIUM

no
ASUS RT AC51U does not support inter-VLAN routing. 22.2% of routers support inter-VLAN routing.
VLAN tagging
What it is: Lets the router mark traffic with VLAN tags for segmented or ISP-specific network setups.
When it matters: When you separate guest, office, IoT, or ISP-required traffic into different network segments.

Importance: MEDIUM

?
QoS
What it is: Provides quality-of-service controls that prioritize some traffic over less important traffic.
When it matters: When calls, gaming, and downloads compete and you want latency-sensitive traffic protected.

Importance: HIGH

yes
ASUS RT AC51U includes QoS controls. 2.7% of routers include QoS controls.
Show more
N. of LAN ports
What it is: Measures how many LAN ports the router includes. A higher count expands direct connectivity for matching devices.
When it matters: When you run a home office with NAS, TV boxes, and desktops, having more LAN ports avoids extra switches and keeps latency lower on wired links.

Importance: HIGH

Good value: 4 ports

4
ASUS RT AC51U has 4 LAN ports, which is more than 23.4% of routers and the same as 69.5% of routers.
LAN port speeds
What it is: Lists the Ethernet speeds available on the router’s LAN ports, such as Gigabit or multi-gig.
When it matters: When wired transfers to NAS, desktops, or access points need more than basic Ethernet speeds.

Importance: HIGH

Good value: 1 Gbps

100 Mbps
ASUS RT AC51U offers 100 Mbps on its LAN ports, which is slower than 73.1% of routers and on par with 26.4% of routers.
N. of WAN ports
What it is: Shows how many separate WAN uplink ports the router provides for internet connections.
When it matters: When you use dual internet lines, backup WAN, or load balancing between multiple external links.

Importance: HIGH

Good value: 1 WAN port

1
ASUS RT AC51U has 1 WAN ports, which is more than 1% of routers and the same as 90.1% of routers.
N. of USB ports
What it is: Shows how many USB ports the router includes for storage, printers, or modem accessories.
When it matters: When you plan to share storage, attach a printer, or use USB-based network extras.

Importance: MEDIUM

Good value: 1 USB port

1
ASUS RT AC51U has 1 USB ports, which is more than 39.2% of routers and the same as 39.9% of routers.
Power over Ethernet (PoE)
What it is: Power over Ethernet support, meaning the router can receive power, deliver it, or be part of a PoE-based installation.
When it matters: When you want cleaner installation with fewer separate power cables, especially in ceilings, walls, racks, or remote locations.

Importance: MEDIUM

no
ASUS RT AC51U does not support Power over Ethernet (PoE). 0.5% of routers can be powered over Ethernet.
Show more
Management interface
What it is: Shows how the router is configured and monitored, such as web UI, app, or command-line tools.
When it matters: When setup depth and day-to-day admin convenience are part of the buying decision.

Importance: HIGH

Web UI, App
ASUS RT AC51U uses Web UI, App for management, which is more advanced than 33.4% of routers and equal to 57% of routers.
Firmware upgrade method
What it is: Describes how router firmware updates are installed, such as automatic OTA, web UI, or manual upload.
When it matters: When you want security fixes and new features applied with less maintenance friction.

Importance: HIGH

Web UI, App, Automatic
ASUS RT AC51U supports Web UI, App, Automatic firmware update methods, which are more convenient than 78.9% of routers and equal to 19.9% of routers.
Traffic monitoring
What it is: Lets the router track bandwidth usage by device, app category, or time period.
When it matters: When you need to find which devices or activities are causing slowdowns or high data use.

Importance: MEDIUM

yes
ASUS RT AC51U includes traffic monitoring. 17.5% of routers include traffic monitoring.
Guest Wi-Fi network
What it is: Lets the router create a separate wireless network for visitors or less-trusted devices.
When it matters: When guests need internet access without reaching private devices on the main network.

Importance: HIGH

yes
ASUS RT AC51U offers a guest Wi‑Fi network. 8.6% of routers offer a guest Wi‑Fi network.
Captive portal
What it is: Supports a login or acceptance page that users must pass before getting internet access.
When it matters: When guest networks, rentals, cafes, or managed access points need a sign-in page.

Importance: MEDIUM

no
ASUS RT AC51U does not offer captive portal features. 23.9% of routers offer captive portal features.
Show more
CPU clock speed
What it is: Shows the operating frequency of the router processor, often listed per core.
When it matters: When routing, encryption, QoS, and many active clients can put heavier load on the CPU.

Importance: HIGH

0.9 GHz
ASUS RT AC51U runs at 0.9 GHz, which is slower than 55.9% of routers and on par with 0.3% of routers.
RAM capacity
What it is: The amount of working memory available for sessions, routing tables, and running router services.
When it matters: When many devices, VPN tunnels, or advanced features need the router to stay responsive under load.

Importance: HIGH

Good value: >=512 MB

64 MB
ASUS RT AC51U has 64 MB of RAM, which is less than 66.9% of routers and the same as 15.2% of routers.
Internal storage
What it is: The built-in storage available for logs, apps, shared files, or other local router functions.
When it matters: When the router runs extra services and needs space for logs, packages, or shared content.

Importance: MEDIUM

Good value: >=8 GB

0.007812 GB
ASUS RT AC51U has 0.007812 GB of internal storage, which is less than 73.1% of routers and the same as 20.3% of routers.
Hardware acceleration
What it is: Uses dedicated hardware paths to offload routing, NAT, encryption, or switching tasks from the main CPU.
When it matters: When heavy routing or security features would otherwise reduce throughput on the processor alone.

Importance: HIGH

no
ASUS RT AC51U does not offer hardware acceleration. 81% of routers offer hardware acceleration.
N. of external antennas
What it is: Shows how many antennas are mounted externally on the router.
When it matters: When you want stronger adjustable coverage or plan to aim antennas for difficult room layouts.

Importance: MEDIUM

Good value: 3 antennas

2
ASUS RT AC51U has 2 external antennas, which is more than 45% of routers and the same as 13.3% of routers.
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ASUS RT AC51U vs the average router

  • Supports automatic failover
    ASUS RT AC51U offers automatic failover, while the average router does not. 24.5% of routers offer automatic failover.
    What it is: Can switch to a backup internet connection automatically if the primary line fails.
    When it matters: When uptime matters and the network cannot stop every time the main WAN drops.

    Importance: MEDIUM

    ASUS RT AC51U offers automatic failover, while the average router does not. 24.5% of routers offer automatic failover.
  • 5.67 W lower power consumption
    ASUS RT AC51U uses less power than the average router (2.4 W vs 8.1 W). The average router uses 8.1 W power.
    What it is: The amount of electrical power the router draws during normal operation, usually measured in watts.
    When it matters: When the router stays on all day and you care about heat output and long-term electricity cost.

    Importance: MEDIUM

    Good value: <6 W

    ASUS RT AC51U uses less power than the average router (2.4 W vs 8.1 W). The average router uses 8.1 W power.2.43 W vs 8.1 W
  • 10.6% higher user score
    ASUS RT AC51U has a higher user score than the average router (8.85 vs 8,000).
    What it is: A rating that combines user reviews and the total number of reviews received by the router.
    When it matters: When you want to know how a router performs in daily use and how reliable it is for speed, coverage, and stability according to user feedback.
    ASUS RT AC51U has a higher user score than the average router (8.85 vs 8,000).8.85 vs 8
  • 2.57x cheaper
    ASUS RT AC51U is cheaper than the average router (£35 vs £90).
    ASUS RT AC51U is cheaper than the average router (£35 vs £90).£35 vs £90
  • Supports automatic failover
    ASUS RT AC51U offers automatic failover, while the average router does not. 24.5% of routers offer automatic failover.
  • 5.67 W lower power consumption
    ASUS RT AC51U uses less power than the average router (2.4 W vs 8.1 W). The average router uses 8.1 W power.

Total
Overall
Networking
Hardware
  • 49.4% 40% slower Wi-Fi speed
    ASUS RT AC51U has a lower Wi-Fi speed than the average router (733 Mbps vs 1,450 Mbps). The average router reaches Wi-Fi speed of 1,450 Mbps.
  • No band steering
    ASUS RT AC51U does not support band steering, while the average router does. 52.6% of routers support band steering.
  • 1 2 fewer spatial streams
    ASUS RT AC51U has fewer spatial streams than the average router (1 vs 2). The average router has 2 spatial streams.
  • Slower LAN ports
    ASUS RT AC51U has a lower LAN port speed than the average router (100 Mbps vs 1 Gbps). The average router has LAN port speed of 1 Gbps.
  • Less capable NAS services
    ASUS RT AC51U includes SMB, FTP, media server NAS services, while the average router includes SMB, FTP, time machine, NFS, web access.
  • No hardware acceleration
    ASUS RT AC51U does not offer hardware acceleration, while the average router does. 80.7% of routers offer hardware acceleration.
  • 50% 2 GB less RAM
    ASUS RT AC51U has less RAM than the average router (64 MB vs 128 MB). The average router has 128 MB of RAM.
  • Slower LAN ports
    ASUS RT AC51U has a lower LAN port speed than the average router (100 Mbps vs 1 Gbps). The average router has LAN port speed of 1 Gbps.
    What it is: Lists the Ethernet speeds available on the router’s LAN ports, such as Gigabit or multi-gig.
    When it matters: When wired transfers to NAS, desktops, or access points need more than basic Ethernet speeds.

    Importance: HIGH

    Good value: 1 Gbps

    ASUS RT AC51U has a lower LAN port speed than the average router (100 Mbps vs 1 Gbps). The average router has LAN port speed of 1 Gbps.100 Mbps vs 1 Gbps
  • No hardware acceleration
    ASUS RT AC51U does not offer hardware acceleration, while the average router does. 80.7% of routers offer hardware acceleration.
    What it is: Uses dedicated hardware paths to offload routing, NAT, encryption, or switching tasks from the main CPU.
    When it matters: When heavy routing or security features would otherwise reduce throughput on the processor alone.

    Importance: HIGH

    ASUS RT AC51U does not offer hardware acceleration, while the average router does. 80.7% of routers offer hardware acceleration.
  • 49.4% 40% slower Wi-Fi speed
    ASUS RT AC51U has a lower Wi-Fi speed than the average router (733 Mbps vs 1,450 Mbps). The average router reaches Wi-Fi speed of 1,450 Mbps.
    What it is: The advertised maximum wireless throughput rating of the router under supported conditions.
    When it matters: When several users stream, download, and game at once and you want more wireless headroom.

    Importance: HIGH

    Good value: >2700 Mbps

    ASUS RT AC51U has a lower Wi-Fi speed than the average router (733 Mbps vs 1,450 Mbps). The average router reaches Wi-Fi speed of 1,450 Mbps.733 Mbps vs 1,450 Mbps
  • No band steering
    ASUS RT AC51U does not support band steering, while the average router does. 52.6% of routers support band steering.
    What it is: Can guide dual-band or tri-band clients toward the more suitable frequency band automatically.
    When it matters: When you want devices spread more intelligently across 2.4, 5, or 6 GHz bands.

    Importance: LOW

    ASUS RT AC51U does not support band steering, while the average router does. 52.6% of routers support band steering.
  • Less capable NAS services
    ASUS RT AC51U includes SMB, FTP, media server NAS services, while the average router includes SMB, FTP, time machine, NFS, web access.
    What it is: Lists the onboard file-sharing services the router can provide, such as SMB, FTP, or media sharing.
    When it matters: When the router is expected to handle light file serving without separate NAS hardware.

    Importance: MEDIUM

    ASUS RT AC51U includes SMB, FTP, media server NAS services, while the average router includes SMB, FTP, time machine, NFS, web access.SMB, FTP, media server vs SMB, FTP, time machine, NFS, web access
  • 50% 2 GB less RAM
    ASUS RT AC51U has less RAM than the average router (64 MB vs 128 MB). The average router has 128 MB of RAM.
    What it is: The amount of working memory available for sessions, routing tables, and running router services.
    When it matters: When many devices, VPN tunnels, or advanced features need the router to stay responsive under load.

    Importance: HIGH

    Good value: >=512 MB

    ASUS RT AC51U has less RAM than the average router (64 MB vs 128 MB). The average router has 128 MB of RAM.64 MB vs 128 MB
  • 1 2 fewer spatial streams
    ASUS RT AC51U has fewer spatial streams than the average router (1 vs 2). The average router has 2 spatial streams.
    What it is: Shows how many parallel Wi-Fi spatial streams the router can use for wireless data transmission.
    When it matters: When modern clients need higher throughput from wider multi-stream Wi-Fi connections.

    Importance: MEDIUM

    Good value: 4 spatial streams

    ASUS RT AC51U has fewer spatial streams than the average router (1 vs 2). The average router has 2 spatial streams.1 vs 2
Total
Wireless
Ports
Management
Hardware

Graphic comparison of ASUS RT AC51U and other routers

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Third-party reviews

United Kingdom
amazon
4.2
4779 Reviews
amazon
4.0
384 Reviews
amazon
4.0
154 Reviews
United States
Amazon_logo.png
4.3
869 Reviews
Amazon_logo.png
4.0
372 Reviews
Amazon_logo.png
4.0
154 Reviews
Amazon_logo.png
3.1
10 Reviews

(Reviews last updated: May 2026)

What customers like about ASUS RT AC51U?

  • Excellent value for money and very affordable price point
  • Intuitive ASUSWRT interface and powerful mobile app for easy setup and management
  • Multipurpose USB port supports file sharing, printer sharing, and 3G/4G dongles
  • Stable performance for basic home tasks with simultaneous dual-band support
  • Low energy consumption (only 5W during operation)
  • Includes useful advanced features like VPN server (PPTP), Guest SSIDs, and AiCloud

What customers dislike about ASUS RT AC51U?

  • Limited to 100Mbps Ethernet ports (both WAN and LAN), which bottlenecks faster fiber connections
  • Weak Wi-Fi signal penetration through thick walls or over long distances
  • Lacks support for Apple Time Machine backups on USB-attached storage
  • VPN server performance can be slow with high-level encryption (e.g., OpenVPN)
  • USB port stability can sometimes be inconsistent according to some users

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