The Results - AC580 Client
The tests with a smartphone client provide another look at the potential benefits that throwing up to almost half a grand at your Wi-Fi problems might bring. Smartphones not only have lower class 1x1 radios, but also generally poorer Wi-Fi performance, given all the other radios and antennas that have to be crammed into them.
The reference throughput measurements from the NETGEAR R7000 this time were: 2.4 GHz dn - 30.1 Mbps; 2.4 GHz up - 12.3 Mbps; 5 GHz dn - 56 Mbps; 5 GHz up - 18.5 Mbps.
The 2.4 GHz downlink tests show the worst performer was ASUS' AC3100 class RT-AC88U, with 55% lower throughput. NETGEAR's AC2350 class R7500v2 was next worst (or best), moving into the gain side with 11% throughput improvement. The best performer this time was NETGEAR's R8500. So maybe those amplified antennas do help! ASUS's AC5300 class router isn't far behind, though, with its plain ol' standard antennas.
2.4 GHz Downlink Throughput Change - AC580 Client
2.4 GHz uplink results have the NETGEAR and ASUS again in the #1 and #2 spots, but with the NETGEAR widening the lead with 134% gain vs. the ASUS' 96%. Worst performers again were the two dual-radio 4x4 routers.
2.4 GHz Uplink Throughput Change - AC580 Client
The 5 GHz downlink again show an almost equal number of losers and gainers. The largest gain came from ASUS' RT-AC3200 using Channel 44. The two AC5300 class routers ended up with only modest gains, both using Channel 44.
5 GHz Downlink Throughput Change - AC580 Client
5 GHz uplink produced the largest difference between the ASUS and NETGEAR AC5300 routers, with the ASUS producing a 31% throughput gain and the NETGEAR a 22% loss using the Channel 44 results. The Channel 153 results still put the ASUS ahead of the NETGEAR with losses of 21% and 33%, respectively.
5 GHz Uplink Throughput Change - AC580 Client
That's a lot of data to absorb. So let's look at two summary plots. This is the same data, just presented in a different way. Both plots sum the four throughput changes and sort the products based on the totals. Once again, AC3200 and AC5300 "tri-band" routers have two sets of results.
The first plot shows results for the N600 client. It's clear that there are generally more gains in 2.4 GHz than 5 GHz. In fact, no product produces significant throughput gain in both bands. The best of the bunch is the ASUS RT-AC5300, which produces throughput gain in all cases except perhaps where it most counts: 5 GHz downlink. Its competition, NETGEAR's R8500, comes in third or second (the ASUS RT-AC5300 Channel 44 results are in the #2 slot), but only with its amplified antennas using Channel 44. The R8500 drops into seventh place using Channel 153 results.
Throughput Change Summary - N600 client
Using the 1x1 AC850 smartphone client produces very different results. The top slot goes to ASUS' RT-AC3200, which produced the highest 5 GHz gains of 37% dowlink and 149% uplink. The only other router to produce 5 GHz band up and downlink gains was the much more expensive ASUS RT-AC5300.
Throughput Change Summary - AC580 client
If you're looking for significant gains in 5 GHz performance, ain't none of the newer routers that will likely do much better than the AC1900 router you already own. It looks like they can help squeeze out more 2.4 GHz throughput where you currently get a signal, and maybe turn a marginal location into a more reliable one. But you don't have to spend $500 for that; older AC3200 routers appear to provide just as good 2.4 GHz throughput gains. AC3200's also are a lot cheaper and have the benefit of over a year out in the wild. This should give them the advantage of being more stable via bugfix firmware updates.
AC3200's can also help in the 5 GHz band, but not with higher throughput per se; the data shows that's unlikely. Instead, two 5 GHz radios help prevent bandwidth wasted by slower devices competing for time on a single radio. By letting your faster devices actually run faster, airtime will be used more efficiently, more bandwidth will be freed up and your Wi-Fi network should run more smoothly.
But "tri-band" routers aren't a slam dunk. The Smart Connect feature that is supposed to automatically assign clients to radios is implemented very differently from router to router. And even when it's done well, some devices will just refuse to cooperate and constantly disconnect or insist on connecting to the "wrong" radio, reducing throughput for the devices that are properly assigned. Fortunately, Smart Connect can be disabled and clients manually assigned to a radio. But that's more work and requires your family members cooperate and use only the proper SSID for each device.
If you want to give AC3200 a shot, I'd recommend trying TP-LINK's Archer C3200. Its flavor of Smart Connect steers clients between 2.4 and 5 GHz (not all Smart Connect routers do) and produced the most consistent total throughput improvement of any tri-band router we've tested yet. And it's a hell of a lot cheaper than the latest Wi-Fi science experiments that we now know aren't going to work the miracles you're looking for!