Arch Linux

daniel_shub

Member

Registered: 2012-06-21

Posts: 89

Bad WiFi RX performance

I have a laptop running Arch Linux with an Intel Corporation Alder Lake-P PCH CNVi WiFi (rev 01) card and I am getting asymmetrical TX and RX speeds as measured by iperf3

$ iperf3 -c 192.168.101.1 --bidir

- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID][Role] Interval           Transfer     Bitrate         Retr
[  5][TX-C]   0.00-10.00  sec   417 MBytes   350 Mbits/sec    1             sender
[  5][TX-C]   0.00-10.04  sec   414 MBytes   346 Mbits/sec                  receiver
[  7][RX-C]   0.00-10.00  sec  29.1 MBytes  24.4 Mbits/sec    1             sender
[  7][RX-C]   0.00-10.04  sec  26.2 MBytes  21.9 Mbits/sec                  receiver

My network consists of a router (192.168.101.1) running OpenWRT with a Unifi UAP-AC-IW AP on a 5 GHz channel with an 80 MHz bandwidth. I am pretty happy with the 350 Mbps TX speed, but the 20-25 Mbps RX speed is much slower than I would expect.

I am pretty sure this is a configuration issue with my laptop since I get good RX and TX speeds between the router and my phone (192.168.101.123). The app on my phone does not support --bidir testing, but I ran the app as both a server and a client and then copied the results from the router.

# iperf3 -c 192.168.101.123
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   343 MBytes   288 Mbits/sec    0             sender
[  5]   0.00-10.04  sec   340 MBytes   284 Mbits/sec                  receiver

# iperf3 -s
-----------------------------------------------------------
Server listening on 5201 (test #1)
-----------------------------------------------------------
Accepted connection from 192.168.101.123, port 49554
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-5.06   sec   165 MBytes   273 Mbits/sec                  receiver

Any idea what I might have screwed up or where to look?