Four Stream Performance
NETGEAR supplied two R8500s so 4x4 thoughput could be tested. This is the first look I've had at Broadcom's 4x4 chipset and I was interested to see if it could achieve the advertised maximum link rates made possible by 1024-QAM modulation. In short, it couldn't, even after I delayed this review for two weeks waiting for NETGEAR to release new firmware that was supposed to improve bridge performance.
For the test, two R8500s were set up in open air, eight feet apart, one as a normal router and the other in wireless bridge mode (found in Advanced > Wireless Settings> use other operation mode > Enable Bridge mode). The in-house 5 GHz network was idle and only beaconing (no traffic). Channel was set to 153, bandwidth mode was in its default Up to 2165 Mbps mode and everything else was set to defaults.
I connected only one computer via Gigabit Ethernet at each end of the bridge. Baseline tests using Ethernet between the two computers (both equipped with TP-LINK TG-3468 NICs) show the Ethernet link capable of a bit over 940 Mbps in both directions with each direction run separately. So the hardwired part of the link shouldn't be a limiting factor.
I started out running simultaneous up and downlink tests as I have in past reviews. But I had to abandon that approach because uplink throughput was so poor, both before and after NETGEAR's firmware update. Instead, I ran four simultaneous IxChariot connections, which yielded only 708 Mbps total downlink throughput as shown below.
Four stream throughput - 5 GHz downlink
5 GHz uplink produced only 181 Mbps total throughput. I tried this test many times, rebooting both routers and even the computers running the tests. Nothing changed the results. I monitored the link rate using the wireless status reported by the bridge. The most I saw was 1625 Mbps; not even close to the 2165 Mbps I should have been seeing.
Four stream throughput - 5 GHz uplink
Thinking it could perhaps be the upper band internal antennas, I retried the test, this time using the lower band radio set to Channel 44, bringing the external antennas into play. This raised total downlink throughput over 100 Mbps to 823 Mbps.
Four stream throughput - 5 GHz downlink, Channel 44
It didn't do anything to help uplink throughput, which stayed almost the same as before. The best link rate I saw during this second trial remained 1625 Mbps.
Four stream throughput - 5 GHz uplink, Channel 44
Since 1024-QAM is supposed to increase the maximum 2.4 GHz link rate to 1000 Mbps, I reran the tests with the 2.4 GHz radio set to Channel 6 and Up to 1000 Mbps mode. The reported link rate of 900 Mbps was closer to the 1000 Mbps I should have been seeing, and the test yielded 433 Mbps of total downlink throughput.
Four stream throughput - 2.4 GHz downlink
2.4 GHz uplink appeared to not share the problems 5 GHz uplink had. Total throughput for this test produced 420 Mbps; almost equal to downlink. Looking at both plots, however, shows throughput was not equally distributed among the test streams.