Nice set of features
The WRT1900AC shares the same interface as that of previous Smart Wi-Fi routers but with many improved features. The Network Map now has a lot of customizations -- you can view connected devices by connection types (wireless or wired) or device types (computers, mobile devices, printers, and unknown). You can quickly add or edit a connected client to a IP reservation/blocking pool, give it a name, or view more information about the client. In all, the Map is a great feature for anybody to visually manage their home network.
The second big feature is the Media Prioritization, which allows you to drag and drop connected clients between the High priority and Normal priority lists. (The former will have priority access to the Internet.) There's also a handy Internet Speed test (available only locally) and a simple Parental Control feature that allows you to block certain connected clients' access to the Internet or just to certain Web sites. You can also schedule the time when the blocking is in effect. With the WRT1900AC, you can change the name of its guest networks (two of them, one for each band) to what you prefer, a first among Linksys Smart Wi-Fi routers. With previous models, the guest networks' names would be based on the name of the main networks with a "-guest" suffix. You can allow up to 50 guests at a time.
The router's USB ports can be used to connect to external storage devices of any capacity. You can use external hard drives formatted in HFS+, FAT32, or NTFS. In my trials, while the USB 2.0/eSATA port worked well, the USB 3.0 port didn't provide enough juice to power a few of the portable drives. (It did with most drives, however.) When a drive is plugged in, you can share its content with other network devices, either via regular file-sharing protocol or through streaming. By default, all clients in your home network can access all the content stored on a connected drive, but you can also turn on secure sharing by user accounts. The router supports UPnP and DNLA streaming standards, meaning content stored on the connected drive can be played back by network media streamers.
Other than that, the WRT1900AC offers all the other common features and settings found in most new routers, such as IPv6, DynDNS, port-forwarding, WPA/WPA2 Wi-Fi encryption methods, and so on. However, for first-time Smart Wi-Fi router users, the interface might require a learning curve. It also doesn't provide the level of customization they might like for the Wi-Fi networks.
Miscategorization and lack of customizations
While very organized and for the most part self-explanatory, the layout of the WRT1900AC's Web interface might be confusing to those who have never used it before. This is because you don't find the standard categories, such as Administration, Basic, Advanced, System, and so on. Instead there are four categories under Router Settings, including Connectivity, Troubleshooting, Wireless, and Security and each of those doesn't necessarily contain the information you are looking for.
For example, MAC filtering -- a security feature that blocks a client from connecting using its MAC address -- is not shown under Security, or even Connectivity. Instead, you'll find it in the Wireless section. Similarly, the Dynamic DNS and port-forwarding are filed under Security rather than under Connectivity. You'll find firmware updates in the Connectivity section instead of Troubleshooting, and so on and so forth. Basically, you have to dig around in the interface to find what you need, and if you feel like a common setting is missing, chances are it's just hidden somewhere.
The interface doesn't allow for customizing the Wi-Fi network, either. For example, on the 5GHz band, you change its setting to Auto, N-only, A-only, or A/N, but you can't make it work in AC-only mode. You can't pick a frequency higher than 40MHz, either. While this is not a big deal, and chances are the Auto setting (the default) will get the job done. However, savvy users will miss the ability to customize the Wi-Fi networks to their own preferences; for example, making the 5GHz work only with AC clients to get the best speed.
Excellent Wi-Fi performance, unprecedented NAS speed
I tested the WRT1900AC's Wi-Fi performance on the "Auto" setting for both the 5GHz and 2.4GHz bands -- since this is the only way for it to offer top speeds -- and it performed very well.
On the 5GHz band, I noted that the clients could connect to the router easily at 1.3Gbps. At close range (15 feet), I got a sustained copy speed of 65MBps (or 521Mbps). When I increased the distance to 100 feet, that speed now registered at 341Mbps. Both of these scores are among the fastest on the market.
On the 2.4GHz band, it was a little different story. It seemed that on the Auto setting, the clients didn't connect to the router consistently at the same rate, but that changes between 175Mbps and 600Mbps. In the end, the average score was 168Mbps for close range and about 50Mbps at long range. These aren't slow, but comparatively they're not among the fastest, either.
I was also very pleased with the router's Wi-Fi range, which was among the farthest I've seen --up to more than 300 feet in my testing. Obviously the closer you are, the better data rates you'll get, and the effective range of this model is about the same as other high-end router -- around 175 feet or less. The router also passed my 48-hour stress test without a hiccup. During this time of transferring large amounts of data between multiple Wi-Fi clients it didn't disconnect once.
Note that I tested the router at CNET's offices, where there are walls and many Wi-Fi devices that are out of my control. Generally, walls shorten the reach of a Wi-Fi signal, and other Wi-Fi devices create interference. As with all Wi-Fi routers, your results may vary depending on where you live.
The WRT1900AC's NAS performance was the most impressive. When couple with a portable drive connected to its USB 3.0 port via a gigabit connection, the router registered a sustained speed of 75MBps for writing and 105MBps for reading. These are by far the fastest among all routers that have this feature, and even faster than many high-end dedicated NAS servers.
Despite its high-end components, the WRT1900AC managed to stay cool during my testing. It never became hot enough to trigger the little ventilation fan on the inside. For this reason, it was also very quiet.
The WRT1900AC is easily the best Wi-Fi router Linksys has made in a long time, and it's one of the best 802.11ac routers on the market. To add to its value, there will soon be third-party firmware made for this router. This means, among other things, if you're taken aback by its interface, you'll have a choice to change to an entirely different one.
The only real drawback is its hefty price. If you plan on using it as a NAS server (with your own add-on storage, of course) -- or if you plan on taking advantage of the custom firmware option -- it's well worth it. Otherwise, you'll want to check out the Netgear R7000 and the Asus RT-AC68U instead; both are also great routers at lower prices.