|At a glance
|Linksys AC1900 Dual Band Wireless Router (WRT1900ACS) [Website]
|Second version of Marvell-based AC1900 class router with Gigabit Ethernet ports and USB 3.0 / eSATA storage sharing
|• High performance storage sharing
• OpenVPN server
• OpenWRT support
• Supports non WDS bridging and repeating
|• Smaller feature set than other top-end routers
• Poorer 2.4 GHz performance than original
Updated 2/25/16 – Router performance retest due to measurement process error
Linksys’ WRT1900ACS Dual-Band Gigabit Router is the official name for the WRT1900ACV2 that was outed via firmware release notes back in April. The ACS replaces the original WRT1900AC, which will be gone when the last one is sold.
From the outside, the ACS looks the same as the original. But inside, the ACS has lost the fan, upgraded to a 1.6 GHz dual-core Marvell Armada 38X processor, doubled RAM to 512 MB and integrated the two Marvell radios onto the main board. Everything else remains the same including the four-antenna design, USB 3.0 and eSATAp combination USB 2.0 / eSATA ports.
Linksys WRT1900AC and ACS
The WRT1900AC review has the indicator and connector callout info. It hasn’t changed from the original review, so I’m not repeating it here.
Although it looks the same from the outside, the ACS’ innards have gotten a major overhaul with an eye toward cost reduction and more streamlined manufacturing. The new board takes many design cues from the WRT1200AC’s board. In fact, near as I can tell, the ACS’ board is the 1200AC’s board, with all four RF chains loaded.
The photo below shows the new sans-fan layout. RF is still on the right and its "can" is no longer it topped by a heatsink. The processor / memory heatsink on the left isn’t as hefty as the original’s and no longer covers the components below the RF can.
Linksys WRT1900ACS board
For comparison, here’s the original AC’s layout. The RF can’s heatsink was removed for the photo.
Linksys WRT1900AC board
Removing the heatsinks and RF can tops provides a clearer picture of the main board. The two Marvell 88W8864 radios and associated components are now integrated on board.
Linksys WRT1900ACS board – naked
Here’s the WRT1200AC’s board so you can see the, uh, similarities.
Linksys WRT1200AC board – naked
The original WRT1900AC had both radios on a module that was removed for the photo below.
Linksys WRT1900AC board – naked
Here’s a look at inside of the original AC’s module.
Linksys WRT1900AC radio module
Table 1 compares the key components of the old and new designs, plus the WRT1200AC for good measure. I was able to identify switches and receive LNAs (low noise amplifiers) in the ACS’ design. I didn’t inspect the original AC’s board, so don’t know if it also has LNAs.
|Marvell Armada 38X dual-core @ 1.6 GHz
(88F6820-A0 C160) (ARMv7)
|Marvell MV78230 Armada XP @ 1.2 GHz (ARMv7)
|Marvell Armada 38X dual-core @ 1.33 GHz (88F6820-A0 C133) (ARMv7)
|2.4 GHz Radio
– Skyworks SE2623L 2.4 GHz power amplifier (x4)
– Unidentified switch and LNA (x4)
– Skyworks SE2623L 2.4 GHz Power Amp (x4)
– Skyworks SE2623L 2.4 GHz Power Amp (x2)
|5 GHz radio
– RFMD RFPA5522 5 GHz power amplifier (x4)
– Skyworks SKY85601 5 GHz LNA + switch (x4)
– Skyworks SKY85402 5 GHz Power Amp (x4)
– RFMD RFPA5522 4.9 GHz to 5.925GHz WiFi Integrated PA module (x2)
– Skyworks SKY85601 4.9 – 5.9 GHz SPDT Switch with LNA (x2)
Table 1: Component summary
The WRT1900ACS itself doesn’t add any new features. It’s still based on Linksys’ aging "Smart WiFi" OS that we thoroughly explored in the AC’s review. But OpenVPN server support was added back in May, so let’s take a quick look at it.
The OpenVPN controls are pretty simple. Everything you can set is shown below. Note only 5 IP addresses will be issued to clients.
OpenVPN Server settings
The clientconfig.ovpn file downloaded by hitting the OVPN Profile button shows the ACS’ OpenVPN implementation is set to use TUN mode, which keeps DHCP servers on both ends of the connections separate. You can’t switch to bridged TAP mode, as you can in ASUS’ OpenVPN implementation.
That’s ok, though, since everything worked ok when I copied the clientconfig.ovpn file into the OpenVPN client’s config folder installed on the Windows 8 laptop used for testing. Actually, the first connection attempt looked ok, but I couldn’t ping the ACS’ 192.168.1.1 LAN IP from the OpenVPN client.
Once I rebooted everything, I was able to ping ok and connect to another Windows notebook connected to the ACS LAN. Note network browsing isn’t supported, which is a common occurance with VPN connections. Just use UNC notation (\\desired_client_ip) to reach devices on the router’s LAN.
Also don’t use the 172.19.X.X addresses; use the normal router LAN 192.168.1.X addresses when connecting to clients via the OpenVPN tunnel. This Linksys support article walks you through the whole thing pretty well.
Quick throughput tests using drag-and-drop of a 1.15 GB Windows backup (.bkf) file with everything connected via Gigabit Ethernet typically showed 10 – 12 MB/s moving the file from the WRT1900ACS to the OpenVPN client…
OpenVPN Server router-to-client throughput
…and about 1 MB/s on average higher in the client-to-router direction.
OpenVPN Server client-to-router throughput
The Router Charts contain benchmarks for FAT32 and NTFS volume formats with USB 2.0 and 3.0 connections (as applicable). But since we know USB 2.0 is slower and FAT32 has volume and file size limitations, we’ll focus on comparing NTFS format with USB 3.0 connection performance.
The charts below show only AC1900 class routers tested with the latest process. The ACS and AC are in the #1 and #2 slots respectively in both charts. At 106 MB/s, NTFS write performance is 58% faster for the ACS; NTFS read is only 28% faster at 96 MB/s. Simply put, the WRT1900ACS’ storage throughput is within striking distance of saturating a Gigabit Ethernet connection!
Storage Throughput Comparison – NTFS & USB 3.0
Since the Linksys WRTs are the only routers with eSATA ports, the Router Charts don’t include those results. Table 2 includes the WRT1200AC. eSATA results are comparable to USB 3.0 for the most part. eSATA FAT32 results run a bit higher than USB 3.0 (not shown here, but in the Charts).
|Marvell Armada 38X @ 1.6 GHz
|Marvell MV78230 @ 1.2 GHz
|Marvell Armada 38X @ 1.33 GHz
|FAT32 Write (MBytes/s)
|FAT32 Read (MBytes/s)
|NTFS Write (MBytes/s)
|NTFS Read (MBytes/s)
Table 2: File copy throughput – eSATA (MBytes/sec)
Updated 2/25/16 – Router performance retest due to measurement process error
Routing throughput was measured using our standard router test process with the router using 18.104.22.168229 firmware. Table 3 summarizes the results and includes the original WRT1900AC and Linksys EA6900 for comparison.
|WAN – LAN (Mbps)
|LAN – WAN (Mbps)
|Total Simultaneous (Mbps)
|Maximum Simultaneous Connections
Table 3: Routing throughput
The IxChariot unidirectional composite plot shows higher average WAN – LAN throughput, most likely due to the long periods of lower LAN – WAN throughput.
Linksys WRT1900ACS routing throughput unidirectional summary
The simultaneous up/downlink benchmark plot shows LAN – WAN throughput with the upper hand and WAN – LAN seeming to struggle to maintain higher throughput.
Linksys WRT1900ACS routing throughput bidirectional summary
Here’s the AC’s simultaneous throughput plot for comparison.
Linksys WRT1900AC routing throughput bidirectional summary
The WRT1900AC is Wi-Fi Certified for 802.11a,b,g,n and ac. It defaulted to Auto channel mode and width on both 2.4 and 5 GHz radios upon power-up. The router comes with unique 2.4 and 5 GHz SSIDs set, so you don’t have to change anything to connect dual-band clients to the desired band.
WPS was enabled on both bands and a WPS pushbutton session completed quickly on both resulting in WPA2/AES connections.
For throughput testing, the router was first reset to factory defaults. Then Channel 6 and 20 MHz bandwidth mode was set for 2.4 GHz and Channel 153 and 80 MHz mode set for 5 GHz. The test client was connected using WPA2/AES encryption.
The router’s four antenna cluster was centered on the test chamber turntable with all antennas vertical as shown in the photo below. The 0° position for the router had the front facing the chamber antennas.
Linksys WRT1900ACS in test chamber
The Benchmark Summary below shows the average of throughput measurements made in all test locations.
Linksys WRT1900ACS Benchmark Summary
The charts below, filtered to show AC1900 class routers and current test process only, show the WRT1900ACS’ average 2.4 GHz throughput performance over the entire measured range is near the bottom of all AC1900 class routers tested for both down and uplink.
Linksys WRT1900ACS 2.4 GHz Average throughput comparison
The story is very different for average 5 GHz performance, where the ACS sits at the top of both charts.
Linksys WRT1900ACS 5 GHz Average throughput comparison
The 2.4 GHz downlink profile shows the why the ACS did poorly in the average throughput comparison. Although it starts out at the same throughput as the other two routers, throughput starts to fall off 12 dB earlier at 18 dB attenuation.
The ACS’ throughput falloff is a little less steep than the other two routers from 18 to 36 dB of attenuation, where its falloff rate then increases to match the other two routers’.
2.4 GHz Downlink Throughput vs. Attenuation
The 2.4 GHz uplink plot shows the ACS more like the EA6900, although again falling off sooner. The AC’s throughput starts out exceptionally high, but then starts to fall off pretty early. The high start keeps its curve above the others for most of the tested range.
2.4 GHz Uplink Throughput vs. Attenuation
Wireless Performance – more
The 5 GHz downlink profile shows the ACS with much higher starting throughput than the other two routers. This clearly gives it an advantage in total average throughput. From 15 dB attenuation on, however, the AC and ACS track very closely.
5 GHz Downlink Throughput vs. Attenuation
For 5 GHz uplink, the ACS again starts off with the highest throughput of the group, then starts its decline. The AC’s curve jumps around a lot, but starting at 24 dB attenuation tends to track the ACS’. The Broadcom-based EA6900 has the best throughput starting at 21 dB attenuation.
5 GHz Uplink Throughput vs. Attenuation
The WRT1900ACS ranks #7 out of twelve tested AC1900 routers; a pretty disappointing showing. Comparing the Router Ranker Performance Summaries for both products shows sub-ranking details to explain the difference. The sub-ranks tell a Tale Of Two Routers story, with the ACS besting the AC in the 5 GHz band, but coming in a distant second in 2.4 GHz. Wired router ranking cancels out with a tie at #3.
WRT1900ACS Ranker Performance Summary comparison
The WRT1900ACS’ brightest spot continures to be storage performance. Both the original WRT1900AC and WRT1900ACS stand above all other wireless routers we’ve tested of any class in our large sequential filecopy test.
I hate to say it, but Linksys appears to have taken a step backward with the WRT1900ACS, at least for 2.4 GHz performance. If you like everything else about the WRT1900, then grab an AC while you can.
Once they’re gone, your best option in a Linksys AC1900 class router will be the EA6900. With a #3 performance rank and available for as little as $120 new and $100 refurbished direct from Linksys, it currently ranks #1 in bang for the buck in AC1900 class routers.