Hi,
I am facing an interesting, if not strange, issue. I am unable to figure it out, so I thought I would post it to the collective wisdom of R7800 users here, hoping somebody can shine some light on it.
I tested hnyman's 19.07 build (owrt1907-r11333-cc0b70467d-20210409) on R7800 for 5Ghz WiFi bandwidth (80Mhz Channel 36), using iperf3 as server on R7800, and iperf3 client on smartphone with 2x2 MIMO VHT80. Both R7800 and smartphone show link speed of 866.7Mbps e.g. "866.7 Mbit/s, 80 MHz, VHT-MCS 9, VHT-NSS 2, Short GI." in OpenWrt in Associated Station log, for both upload and download. This was a fresh install, with no changes from default other than WiFi config and iperf3 package install.
The iperf3 client was run as "iperf3 -c -t 15 -i 1 -P 6" i.e. with six streams, to max out the bandwidth. The smartphone was held around 1 foot away from router.
The total bandwidth across six streams was between 625Mbps to 650Mbps, which makes sense, given the link speed was 866.67 Mbps. My understanding from iperf3 documentation is that this is the upload bandwidth i.e. upload from smartphone to router.
I then ran the iperf3 client in reverse direction i.e. "iperf3 -c -t 15 -i 1 -P 6 -R". My understanding from iperf3 documentation is that this is the download bandwidth i.e. download from router to smartphone. All other conditions were same, including link speed, distance, etc.
The total bandwidth across six streams was between 275Mbps to 300Mbps. This was verified multiple times, and the results were very consistent. Download is less than half of upload, all else being same!
I then repeated the same test set up with hnyman's 21.02 build (owrt2102-r16051-15cd9a5d5c-20210420) with a fresh install, and no changes from default other than WiFi config and iperf3 package install. The upload was again similar, 625Mbps to 650Mbps. The download improved to between 475Mbps too 500Mbps. It never went above 500Mbps across multiple tests.
What can explain the following?
- Why is download speed less than half of upload speed in WiFi 5Ghz 80Mhz in 19.07 build?
- Why is download speed less than upload speed (although a lot better than 19.07, but still persistently less by 100-150 Mbps) in WiFi 5Ghz 80Mhz in 21.02 build?
Are above results known to be what to expect, or do I need to make any changes to the test setup for better results? Can anybody try to replicate my experiment, and see if they get any different results?
Thanks.