In accordance with the Wi-Fi standards it supports, regardless of how fast your existing Wi-Fi network is, the extension networks created by the EX6100 will be as fast as 433Mbps on the 5GHz band and 300Mbps on the 2.4GHz band. These are the best-case speeds, but in my testing, the extender showed much slower data rates than that.
As an extender on the 5GHz band, at 15 feet away it registered just 43Mbps. On the 2.4GHz frequency, it did much worse, at just about 28Mbps. Compared to other Wi-Fi devices I've reviewed that use the same standards, these speeds were really slow.
When I increased the range to 100 feet, both bands now registered in the neighborhood of 3Mbps to 7Mbps -- and at times even slower. Again, extremely slow compared to the competition.
I also noticed a great increase in latency (also known as lag). The EX6100's extension networks' lag times measured as much as 10 times greater than those of the original Wi-Fi network. That said, with the EX6100, your Wi-Fi clients might see a full-bar connection, but things may still take a long time to get through.
The EX6100 did better as an access point but was still very slow compared to other devices using the same Wi-Fi standards. At close range, it scored some 107Mbps and 36Mbps for 5GHz and 2.4GHz bands, respectively. With the range increased to 100 feet, it now averaged 17Mbps and 9Mbps, respectively.
The EX6100 doesn't have great range by itself either -- especially on the 5GHz band, which only reached about 150 feet, just half of what some other 802.11ac devices I've seen are capable of. The 2.4GHz band is better, at about 200 feet. I found both bands' effective range to be 120 feet, so that's how much extra range you can expect from the EX6100. Keep in mind that you can only achieve that extra range if you place it in the right spot in the house, as I mentioned earlier.
In my stress test, in which the EX6100 was set up to transfer a large amount of data back and forth between multiple Wi-Fi clients continuously for 24 hours, the extender passed successfully on the 5GHz band without disconnecting once. On the 2.4GHz band, however, it disconnected several times.
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, while other Wi-Fi devices can create interference. As with all Wi-Fi routers, your results may vary depending on where you live.
One other point: the EX6100 ran hot in my testing. It wasn't hot enough to cook an egg, but it was still hotter than most networking devices I've seen. During some hot days, make sure it's used in an air-conditioned environment.
Strictly as a range extender, the Netgear EX6100 actually delivers: it does in fact extend the range of your existing Wi-Fi network and gives your Wi-Fi clients full-bar connections significantly farther from the original router. However, you need more than just range to have a robust Wi-Fi network, and this device fails to provide the speed necessary for serious network functions, such as data sharing, online gaming, or media streaming. If you're happy with a connection that's fast enough only for emailing, checking Facebook, or surfing the Web, the EX6100 will get the job done. If you want anything more, it's not really worth the investment.
On the other hand, the EX6100 is a much better device when used as an access point, but in this case it's only suitable for homes that currently already have a non-Wi-Fi router, which is not so common a situation these days.