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).
|Linksys WRT1900ACS||Linksys WRT1900AC||Linksys WRT1200AC|
|Processor||Marvell Armada 38X @ 1.6 GHz||Marvell MV78230 @ 1.2 GHz||Marvell Armada 38X @ 1.33 GHz|
|FAT32 Write (MBytes/s)||93.5||56.0||88.7|
|FAT32 Read (MBytes/s)||104.1||78.0||99.6|
|NTFS Write (MBytes/s)||107.7||65.3||107.3|
|NTFS Read (MBytes/s)||103.3||75.8||101.4|
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 188.8.131.52229 firmware. Table 3 summarizes the results and includes the original WRT1900AC and Linksys EA6900 for comparison.
|Test Description||Linksys WRT1900ACS||Linksys WRT1900AC||Linksys EA6900|
|WAN - LAN (Mbps)||809||631||924|
|LAN - WAN (Mbps)||696||926||844|
|Total Simultaneous (Mbps)||1311||975||1135|
|Maximum Simultaneous Connections||36,261||30,557||15,833|
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.