Asus RT-AC87U Wi-Fi router review: Yes, it’s fast

Asus RT-AC87U
Credit: Michael Homnick
At a Glance
  • Asus RT-AC87U Wi-Fi Router

    TechHive Rating

    The RT-AC87U is supremely fast—when it's paired with a second RT-AC87U configured as a wireless bridge. You should make sure its features and performance fits your needs before plunking down your cash.

We’ve come to crown the new king of Wi-Fi routers: The Asus RT-AC87U is by far the fastest wireless router PCWorld has ever tested.

But before you run out and buy one, know that our pronouncement includes caveats. The RT-AC87U is blistering fast when paired with a second RT-AC87U configured as a wireless bridge, but its performance is somewhat less impressive in other scenarios.

The first thing you’ll notice about the new Asus RT-AC87U is that it has four antennas. It's the first 4x4 router, meaning it supports four spatial streams to deliver a maximum physical link rate of 1734Mbps on the 5GHz frequency band (in 802.11ac mode). It supports three spatial streams on the 2.4GHz frequency band and delivers a maximum physical link rate of 600Mbps—thanks to 256QAM, which few client adapters support. You can expect a more ordinary link rate of 450Mbps with most equipment.

As has become dubious industry practice, Asus sums these numbers and generously rounds up to describe the RT-AC87U as an AC2400 router. Ignore such labels: They’re meaningless.

Asus RT-AC87U Michael Homnick

The Asus RT-87U boasts two firsts: It's the first 4x4 router, and the first router to support Multi-user MIMO.

But antenna count doesn’t necessarily correlate to speed. The Linksys WRT1900AC has four antennas, but only three are used for streaming at any one time. The Netgear Nighthawk X6 has six antennas, but that’s because it can operate two independent 5GHz networks simultaneously. The Nighthawk X6 and the WRT1900AC—as well as the D-Link DIR-880L, the original Netgear Nighthawk, and the older Asus RT-AC68U—all support three spatial streams and deliver maximum link rates of 1300Mbps on the 5GHz band. As you’ll see in the performance section of this review, each of those routers is faster than the RT-AC87U in some scenarios and slower in others.

IEEE wireless networking standards often contain a mix of mandatory and optional elements. With 802.11n, for instance, support for MIMO (multiple input/multiple output) is required, but beamforming support is optional. Devices based on the 802.11ac standard must support beamforming and provide channels with up to 80MHz of bandwidth; support for more than one spatial stream, channels that deliver 160MHz of bandwidth, and MU-MIMO (Multi-user MIMO) are all optional features.

MU-MIMO allows the router to transmit to multiple clients at the same time. With the SU-MIMO (Single-user MIMO) technology that Asus’s competitors rely on, the router can transmit to only one client at a time. These routers support more than one client at once, but they must use time division to do it: Those routers dedicate a slice of time to each client and transmit to them in round-robin fashion.

As is so often the case with next-gen features (see 256QAM, above), MU-MIMO is useless unless the client also supports it. I don’t know of any Wi-Fi adapters that do. Asus’s upcoming EA-AC87 wireless media bridge will, but until that product ships, you’ll need to buy a second RT-AC87U and configure it as a wireless media bridge.

Due to the RT-AC87U’s support for four spatial streams and its MU-MIMO capabilities, some are describing it as the first “wave 2” router. “Wave 2.5” is more like it, because the Quantenna QSR1000 chipset Asus uses remains physically limited to delivering 80MHz of bandwidth on the 5GHz band. The RT-AC87U is outfitted with a second CPU—Broadcom’s BMC4709—to handle its USB ports and operate its 2.4GHz network. the RT-AC87U is equipped with 128MB of flash memory and 256MB of DDR3 RAM.

Feature set

Now that you understand the RT-AC87U’s place in the market, let’s go over the rest of its feature set. The router is enclosed in a black plastic case that slopes from front to back. It can be operated on a flat surface or mounted to a wall. Ventilation slits are located on the sides and the right- and left-hand sides of its bottom. The rear panel houses a gigabit WAN port, a four-port gigabit switch, a USB 2.0 port, a WPS (Wi-Fi Protected Setup) button, a reset button, and a power switch. The router’s four removable antennas are also mounted here.

Asus RT-AC87U Michael Homnick

Apart from the four antennas, the back of the Asus RT-AC87U looks just like any other high-end router.

LEDs indicating the status of power, the 2.4- and 5GHz radios, the ethernet ports, Internet connection, and WPS are located on the front panel. They’re difficult to see if you’re looking at the router from above. Power buttons the LEDs and the Wi-Fi radios are on the left side of the front panel. Removing a panel on the righthand side reveals a USB 3.0 port.

This isn’t a physically convenient location, but Asus’s engineers were probably seeking trying to avoid interference between USB 3.0 and the router’s 2.4GHz radio. (USB 3.0 ports generate noise in the 2.4GHz range that can suppress a router’s performance in that spectrum. If you really want to dig into this phenomenon, Intel has an in-depth white paper on the subject.)

The USB ports can be used to share both a printer and a network-attached storage device at the same time, or you can plug a 3G/4G dongle into one to share a mobile broadband connection. The router comes with both iTunes and UPnP servers for media streaming, and FTP and SAMBA servers for file sharing via the Internet or over your local network.

Asus RT-AC87U Michael Homnick

While not aesthetically appealing, locating the USB 3.0 in the front of the device prevents it from interfering with the RT-AC87U's 2.4GHz radio.

Asus’s Smart Sync feature lets you synchronize an attached USB hard drive with Asus’s Webstorage cloud-storage service. This feature would be much more useful if it also supported other cloud-storage services, such as Google Drive, Dropbox, or Microsoft's OneDrive).

Asus says its adaptive quality of service (QoS) feature can recognize the type of client that connects to the router and prioritize network traffic accordingly. A gaming console or a VoIP device, for instance, will automatically be assigned higher priority than a PC’s Torrent session, for instance. The RT-AC87U’s AiProtection feature —developed by AV vendor Trend Micro—promises to prevent network clients from being infected by malicious servers, and offers some basic parental controls.

Asus RT-AC87U Michael Homnick

No other router provides as many tools for using an attached USB storage device. 

Measured by breadth of features, no other router manufacturer comes close to what Asus offers. Whether you’ll benefit from all those features is another question. Many users will never use all of the RT-AC87U’s bells and whistles. That said, let’s look at this router’s performance.

Performance

To take full advantage of the RT-AC87U’s feature set, you need to pair it with a client that supports the same features. Since there isn’t a client adapter on the market that fits that description, I configured a second RT-AC87U as a wireless bridge and tested it that way—with results that were nothing short of spectacular.

Asus RT-AC87U

The RT-AC87U is screamin' fast when paired with a second RT-AC87U configured as a wireless bridge. (Note: The Netgear R8000 was paired with a Netgear R7000, and D-Link did not submit a second DIR-880L.)

With the client hardwired to the bridge in the same room as the router and separated by nine feet, I measured TCP throughput of 851Mbps. That’s 40 percent faster than the Linksys WRT1900AC, and it’s more than 60 percent faster than the Netgear Nighthawk X6 paired with the original Nighthawk (Netgear did not send two X6’s for me to review. D-Link didn't send a second DIR-880L, either.) The RT-AC87U produced similarly high numbers in the kitchen and home office, but the WRT1900AC proved to be slightly faster when the client was in my home theater.

Asus’s new router was somewhat less impressive when I tested it with Asus’s own 802.11ac USB client adapter (a 2x2 device), finishing in third place when the client was in the bedroom, second place when it was in the kitchen, fourth in the home theater, and in last place when the client was in my home office—65 feet from the router and separated by three walls.

Asus RT-AC87U

Interestingly, the RT-AC87U wasn't as fast as some of its competitors when paired with Asus's 802.11ac USB Wi-Fi adapter.

Your laptop won't have an 802.11ac Wi-Fi adapter onboard unless it's fairly new (even then, it will likely be a 2x2 device. Apple's MacBook Pro is one of the few laptops on the market to come with a 3x3 802.11ac adapter.) For most people, the best onboard Wi-Fi hardware you can expect is a 3x3 802.11n adapter such as the Intel Centrino Ultimate-N 6300 in my AVADirect gaming laptop. In this scenario, as you can see from the chart, the RT-AC87U delivered very good results at close range, but it finished in last place in my two longer-distance tests.

Asus RT-AC87U

The RT-AC87U didn't impress me with its range while operating as a 5GHz 802.11n router.

I also tested the RT-AC87U's performance on the 2.4GHz band. It did well at close range, but it was very strong at longer range.

Asus RT-AC87U

Asus provides very good support for legacy devices. Lots of network devices—particularly IP cameras—still rely on the 2.4GHz frequency band.

As mentioned earlier, the major benefit of MU-MIMO router is its ability to service multiple clients at the same time. Netgear’s Nighthawk X6 makes up for its lack of MU-MIMO support by operating two distinct 802.11ac networks. Based on my findings, that seems to be the better approach—at least for now.

For this test, I connected two Netgear Nighthawk (R7000) routers as wireless bridges and placed one in my home theater (35 feet from the router) and the other in my home office (65 feet from the router). I hardwired a desktop PC to the bridge in my home theater and a laptop to the bridge in my home office, then I streamed data to both at the same time.

Asus RT-AC87U

Is MU-MIMO just poorly implemented in the RT-AC87U's current firmware? Or is Netgear's strategy of operating two distinct 5GHz networks superior?

On this test, the RT-AC87U fell way behind the Nighthawk X6 at both test locations. It beat the WRT1900AC with the client in my home theater, but it was only half as fast as that router with the client in my home office. The Nighthawk X6, meanwhile, was more than 5X faster than the RT-AC87U. Can this be attributed to immature firmware, or is it just a better to operate two distinct networks? It might be too early to determine the answer. For now, I’d recommend the Nighthawk X6 if you need to support many 802.11ac clients at the same time.

USB storage performance

I’ll wrap up my benchmark discussion with a look at how the RT-AC87U performed with a USB 3.0 storage device attached to it. I used a 500GB Western Digital Passport drive formatted NTFS for this test, and I copied a 10GB collection of small files from a hardwired desktop PC to the drive over the network. I then performed the same operation with a single 10GB file (these are both write tests). The final tests were to copy these same collections from the Passport drive to back to the hardwired desktop PC (these are read tests).

Asus RT-AC87U

Asus's RT-AC87U performs well when it comes to sharing a USB 3.0 hard drive over your network, but The Linksys WRT1900AC reigns supreme.

The RT-AC87U performed well in this regard, but the Linksys WRT1900AC was significantly faster at both read tests and when writing the 10GB collection of files. Asus’s router was only slightly faster when writing a single 10GB file, but all the routers I tested beat the Asus RT-AC68U in all four scenarios. The original Nighthawk was faster than the RT-AC87U by a just fraction in only one test. If network-attached storage is important to you, you should go with the Linksys WRT1900AC or a buy a dedicated NAS box.

So who makes the best 802.11ac router?

When it comes to 802.11ac routers, it’s hard to make a bad choice right now. Netgear’s original Nighthawk (aka the R7000) is widely available for about $190. It delivers a better price-to-performance ratio than D-Link’s $182 DIR-880L. The older Asus RT-AC68U is only slightly more expensive, but it doesn’t deliver a strong performance with an attached USB drive.

Stepping up to $250 will get you a Linksys WRT1900AC. It performs well and might be the best choice for people who want network-attached storage without going the full Monty for a dedicated NAS box. The Netgear Nighthawk X6’s $300 street price marks it as the most expensive Wi-Fi router I’ve tested. If you need to support two or more 802.11ac bridges, however, Netgear’s “tri-band” strategy is the best—at least for now.

Asus’s RT-AC87U blows everything else away when it’s paired with a second RT-AC87U configured as a wireless bridge, but I’m not impressed with its MU-MIMO feature so far. In terms of price, Asus splits the difference between the WRT1900AC and the Nighthawk X6 with a street price of $280.

So which one is the absolute best? It really depends on what you need.

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At a Glance
  • TechHive Rating

    The RT-AC87U is supremely fast—when it's paired with a second RT-AC87U configured as a wireless bridge. You should make sure its features and performance fits your needs before plunking down your cash.

    Pros

    • Supremely fast when paired with an 802.11ac bridge
    • Very long list of advanced features
    • Less-expensive than Netgear's Nighthawk X6

    Cons

    • Not the best solution for serving multiple 802.11ac bridges
    • Not the absolute fastest wireless when not paired with a bridge
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