Setup and software
Like so many other modern quality routers, setting up the RT-AC1900P is an absolute breeze. If you have a simple network configuration, the setup process will likely be as straightforward as clicking "next" a few times. From there on the software is straightforward for the most part, since most of the features are easy to find and access.
I did run into a couple minor oddities while working through the initial setup. This is probably a minor quibble, but I found it frustrating that I couldn't copy and paste hardware addresses from the router's device list into the static DHCP setup. Having to type out those addresses by hand doesn't take long, but there shouldn't be a copy-and-paste restriction on those fields to begin with. The other problem I encountered was particularly bizarre. The router password is limited to a mere 16 characters, and neither the Synology RT-2600ac nor my old Asus router with Tomato firmware have any such limitation.
Asus' extra features include a traffic analyzer, a separate guest Wi-Fi network, support for sharing data on external drives, and Time Machine backups. The router supports file sharing through the FTP and Samba protocols, and it can also act as a media server for DLNA-compatible devices. Asus also bakes in a feature called AiCloud, which gives you the option to set a USB-attached drive up as an internet-accessible device. Asus offers access to this feture through its AiCloud app on mobile devices or with any web browser using a custom URL.
Asus' AiProtection suite includes parental controls, website blacklists, and deep packet inspection (DPI). The DPI functionality is powered by TrendMicro databases, and it'll try and stop common malware infections from spreading around the network. Additionally, AiProtection includes a security assessment test that offers advice on setting up a secure network environment.
The router's Adaptive QoS section will let you monitor real-time bandwidth usage not just by device, but also on a per-application basis. With the default settings, the router will identify and track common sites like Amazon or Facebook. Other traffic will fall into more generic categories like General, SSL/TLS, and HTTP. If you have a complicated home network and connectivity is suddenly sluggish, the traffic monitoring could come in handy for narrowing down just which device is chewing up all the bandwidth. The traffic monitoring can also keep track of web browsing history by device.
QoS priority can be set on a per-device or per-application basis, in either adaptive (automatic), traditional, or bandwidth-limiting modes. I have to note that while the basic setup of the router is pretty clear, I found the QoS section a bit less user-friendly. The Bandwidth Monitor screen looks like a mere information page at first glance. However, there's actually drag-and-drop functionality for estabilishing traffic priorization—except you'd never know if you didn't hover the mouse pointer over some of the UI elements.
Meanwhile, the Traffic Analyzer keeps track of traffic in a manner similar to the QoS section, but presents historical reports. Given a time period, you can see which device used how much data, and break it down to which application and which day. If you wanted to see, for example, how much traffic your Xbox used playing Netflix after you fell asleep halfway through binge-watching the new season of Archer, that's definitely possible.
This section is pretty easy to read and work with, and there's even a tutorial video available to get a better idea of how the reports work. There's only one snag, here. There's no way to export report data, something that would come in handy or even be necessary in a business environment. The overal functionality of the Traffic Analyzer is still effective and simple all the same, though.