Archer C6 V3.20 inconsistent and overall poor Wifi performance

Hey, I recently got a cheaper Archer C6 v3.20 as I understood it had good OpenWRT support. Yet the Wifi performance is really inconsistent and overall poor.

Test setup:

  • Laptop, LG Gram. Running Fedora 36.
  • Archer C6 v3.20:

Firmware Version
OpenWrt SNAPSHOT r19863-fd72e595c2 / LuCI Master git-22.167.28356-8effea5
Architecture
MediaTek MT7621 ver:1 eco:3

Running iperf to test speeds I get really inconsistent results, sometimes 70/80/90mbps, while numbers between 5-20 are really common too.
As an example, running iperf to another box in my lan (cable connected):

[ 5] 0.00-1.00 sec 6.25 MBytes 52.4 Mbits/sec 0 280 KBytes
[ 5] 1.00-2.00 sec 4.97 MBytes 41.7 Mbits/sec 0 481 KBytes
[ 5] 2.00-3.00 sec 4.53 MBytes 38.0 Mbits/sec 0 563 KBytes
[ 5] 3.00-4.00 sec 4.88 MBytes 40.9 Mbits/sec 0 669 KBytes
[ 5] 4.00-5.00 sec 3.75 MBytes 31.5 Mbits/sec 0 691 KBytes
[ 5] 5.00-6.00 sec 3.75 MBytes 31.5 Mbits/sec 17 516 KBytes
[ 5] 6.00-7.00 sec 5.00 MBytes 41.9 Mbits/sec 0 580 KBytes
[ 5] 7.00-8.00 sec 3.75 MBytes 31.5 Mbits/sec 0 592 KBytes
[ 5] 8.00-9.00 sec 5.00 MBytes 41.9 Mbits/sec 0 682 KBytes
[ 5] 9.00-10.00 sec 1.25 MBytes 10.5 Mbits/sec 1 50.9 KBytes

Co> nnecting to host 10.15.0.2, port 5444

[ 5] local 10.15.0.155 port 45190 connected to 10.15.0.2 port 5444
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 1.03 MBytes 8.66 Mbits/sec 0 107 KBytes
[ 5] 1.00-2.00 sec 1.18 MBytes 9.90 Mbits/sec 0 157 KBytes
[ 5] 2.00-3.00 sec 2.73 MBytes 22.9 Mbits/sec 0 246 KBytes
[ 5] 3.00-4.00 sec 2.36 MBytes 19.8 Mbits/sec 0 298 KBytes
[ 5] 4.00-5.00 sec 1.99 MBytes 16.7 Mbits/sec 0 320 KBytes
[ 5] 5.00-6.00 sec 2.86 MBytes 24.0 Mbits/sec 0 345 KBytes
[ 5] 6.00-7.00 sec 1.49 MBytes 12.5 Mbits/sec 0 366 KBytes
[ 5] 7.00-8.00 sec 2.24 MBytes 18.8 Mbits/sec 0 366 KBytes
[ 5] 8.00-9.00 sec 764 KBytes 6.26 Mbits/sec 1 369 KBytes
[ 5] 9.00-10.00 sec 764 KBytes 6.25 Mbits/sec 0 29.7 KBytes


[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 17.4 MBytes 14.6 Mbits/sec 1 sender
[ 5] 0.00-10.16 sec 15.5 MBytes 12.8 Mbits/sec receiver

iperf Done.

The performance is consistently bad throughout various devices (laptop, phone, tablet). I can consistently hit 900+ if I connect my laptop with an ethernet cable and do the exact same test.

As a point of reference, with my old ISP router I can get continuous, stable 60/70mbps iirc.

Note: 5GHz doesn't even work. This is in 2.4GHz.

Relevant configs:

Any pointers are appreciated, I'm a bit lost as to how I should debug this.

The 5ghz radio change it from vht160 to vht 80, i.e, make the channel width 80.

That seems to have fixed the 5GHz issue, thank you! I'll be running periodic iperf tests to check performance. Any idea what's going on with the 2.4GHz network?