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lwfinger / rtw88

A backport of the Realtek Wifi 5 drivers from the wireless-next repo.
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Testing rtw_8822bu, feed back. (Slow bitrate) #224

Open WallyZambotti opened 1 month ago

WallyZambotti commented 1 month ago

System information follows at end.

Testing the rtw_8822bu(Simplecom NW621 AC1200 USB2/3 Techkey Wifi Adapter) from rtw88 downstream.

Can confirm USB3 is now working.

Having a bit rate issue on all systems testing exhibiting slow bit rate after initial connection. The two systems:

1) Intel - Ubuntu 22.04.4 Kernel 6.5.0-44 - with rtw88 downstream driver - to 40mhz router - USB3 (system info included) 2) Intel - Ubuntu 22.04.4 Kernel 6.5.0-44 - with mainline rtw88 driver - 80mhz router - USB2

Both systems start with a high bite rate but after several seconds drop to around 135-180mbits and then never raise under net load.

Following is the system info for 1):

$ uname -a Linux WZ-MS-7B51 6.5.0-44-generic #44~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Jun 18 14:36:16 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

$ lsusb Bus 002 Device 003: ID 0bda:b812 Realtek Semiconductor Corp. RTL88x2bu [AC1200 Techkey]

$ lsusb -t /: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/10p, 10000M |__ Port 6: Dev 3, If 0, Class=Vendor Specific Class, Driver=rtw_8822bu, 5000M

$ mokutil --sb-state SecureBoot disabled Platform is in Setup Mode

$ rfkill list all 1: phy3: Wireless LAN Soft blocked: no Hard blocked: no

$ dkms status nvidia/555.42.06, 5.15.0-116-generic, x86_64: installed nvidia/555.42.06, 6.5.0-44-generic, x86_64: installed rtl8812au/4.3.8.12175.20140902+dfsg, 5.15.0-116-generic, x86_64: installed rtl8812au/4.3.8.12175.20140902+dfsg, 6.5.0-44-generic, x86_64: installed rtl8821ce/5.5.2.1, 5.15.0-116-generic, x86_64: installed

$ iwconfig lo no wireless extensions.

eno1 no wireless extensions.

wlxbcec4322ff20 IEEE 802.11 ESSID:"TCS"
Mode:Managed Frequency:5.2 GHz Access Point: 74:83:C2:B5:56:CA
Bit Rate=180 Mb/s Tx-Power=20 dBm
Retry short limit:7 RTS thr:off Fragment thr:off Power Management:on Link Quality=63/70 Signal level=-47 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:923 Missed beacon:0

$ iw reg get global country AU: DFS-ETSI (2400 - 2483 @ 40), (N/A, 36), (N/A) (5150 - 5250 @ 80), (N/A, 23), (N/A), NO-OUTDOOR, AUTO-BW (5250 - 5350 @ 80), (N/A, 20), (0 ms), NO-OUTDOOR, DFS, AUTO-BW (5470 - 5600 @ 80), (N/A, 27), (0 ms), DFS (5650 - 5730 @ 80), (N/A, 27), (0 ms), DFS (5730 - 5850 @ 80), (N/A, 36), (N/A) (5925 - 6425 @ 160), (N/A, 24), (N/A), NO-OUTDOOR (57000 - 66000 @ 2160), (N/A, 43), (N/A), NO-OUTDOOR

$ iw dev phy#3 Interface wlxbcec4322ff20 ifindex 4 wdev 0x300000001 addr bc:ec:43:22:ff:20 ssid TCS type managed channel 40 (5200 MHz), width: 40 MHz, center1: 5190 MHz txpower 20.00 dBm multicast TXQ: qsz-byt qsz-pkt flows drops marks overlmt hashcoltx-bytes tx-packets 0 0 0 0 0 0 0 00

$ iperf3 -c 192.168.10.152 Connecting to host 192.168.10.152, port 5201 [ 5] local 192.168.10.104 port 52594 connected to 192.168.10.152 port 5201 [ ID] Interval Transfer Bitrate Retr Cwnd [ 5] 0.00-1.00 sec 3.86 MBytes 32.3 Mbits/sec 1 284 KBytes
[ 5] 1.00-2.00 sec 9.64 MBytes 80.9 Mbits/sec 0 672 KBytes
[ 5] 2.00-3.00 sec 7.50 MBytes 62.9 Mbits/sec 0 942 KBytes
[ 5] 3.00-4.00 sec 8.75 MBytes 73.4 Mbits/sec 0 1007 KBytes
[ 5] 4.00-5.00 sec 6.25 MBytes 52.4 Mbits/sec 0 1.03 MBytes
[ 5] 5.00-6.00 sec 7.50 MBytes 62.9 Mbits/sec 0 1.16 MBytes
[ 5] 6.00-7.00 sec 7.50 MBytes 62.9 Mbits/sec 0 1.23 MBytes
[ 5] 7.00-8.00 sec 7.50 MBytes 62.9 Mbits/sec 0 1.23 MBytes
[ 5] 8.00-9.00 sec 7.50 MBytes 62.9 Mbits/sec 2 980 KBytes
[ 5] 9.00-10.00 sec 6.25 MBytes 52.4 Mbits/sec 0 1.04 MBytes

[ ID] Interval Transfer Bitrate Retr [ 5] 0.00-10.00 sec 72.2 MBytes 60.6 Mbits/sec 3 sender [ 5] 0.00-10.67 sec 69.4 MBytes 54.5 Mbits/sec receiver

$ cat /etc/modprobe.d/88x2bu.conf blacklist rtw88_8822bu blacklist rtw88_usb blacklist rtw88_8822b blacklist rtw88_core options 88x2bu rtw_switch_usb_mode=1 rtw_led_ctrl=1

$ lsmod | grep rtw rtw_8822bu 12288 0 rtw_usb 28672 1 rtw_8822bu rtw_8822b 233472 1 rtw_8822bu rtw_core 356352 2 rtw_usb,rtw_8822b mac80211 1724416 2 rtw_usb,rtw_core cfg80211 1323008 2 rtw_core,mac80211

dubhater commented 1 month ago

Thank you for your detailed report. Something is still wrong with this chip. Unfortunately I don't have a device to test.

morrownr commented 1 month ago

@dubhater

I have several usb wifi adapters based on the rtl8812bu chip. We can worry about how to put one in your hands as we have time but for now, tell me what you want me to do.

FYI: I've been sick this week. Am starting to feel a little better now.

morrownr commented 1 month ago

@dubhater

Afterthought: The rtl8812bu chip is likely the most popular Realtek chip in the hands of Linux users so it is a priority...once rtw_8821au and rtw_8812au have gone in.

morrownr commented 1 month ago

@dubhater

Test system: x86_64 Debian 12 kernel 6.6 AP: 80 MHz channel width and supports WiFi 5 (actuall it supports WiFi 6 but this adapter in question can't do WiFi 6). Channel 100 (DFS) clean air signal level of -25 dBm, through 2 walls and about 6 meters distance Adapter: rtl8812bu based running as client, managed mode Driver: rtw_8822bu

Here are two runs with iperf3:

$ iperf3 -c 192.168.1.1
Connecting to host 192.168.1.1, port 5201
[  5] local 192.168.1.135 port 35716 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  69.6 MBytes   584 Mbits/sec    0    976 KBytes       
[  5]   1.00-2.00   sec  67.5 MBytes   566 Mbits/sec    0    976 KBytes       
[  5]   2.00-3.00   sec  67.5 MBytes   566 Mbits/sec    0    976 KBytes       
[  5]   3.00-4.00   sec  66.2 MBytes   555 Mbits/sec    0    976 KBytes       
[  5]   4.00-5.00   sec  66.2 MBytes   556 Mbits/sec    0    976 KBytes       
[  5]   5.00-6.00   sec  67.5 MBytes   566 Mbits/sec    0    976 KBytes       
[  5]   6.00-7.00   sec  66.2 MBytes   556 Mbits/sec    0    976 KBytes       
[  5]   7.00-8.00   sec  68.8 MBytes   577 Mbits/sec    0    976 KBytes       
[  5]   8.00-9.00   sec  67.5 MBytes   566 Mbits/sec    0    976 KBytes       
[  5]   9.00-10.00  sec  66.2 MBytes   556 Mbits/sec    0    976 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   673 MBytes   565 Mbits/sec    0             sender
[  5]   0.00-10.01  sec   671 MBytes   563 Mbits/sec                  receiver

$ iperf3 -c 192.168.1.1 -R
Connecting to host 192.168.1.1, port 5201
Reverse mode, remote host 192.168.1.1 is sending
[  5] local 192.168.1.135 port 39732 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  35.0 MBytes   293 Mbits/sec                  
[  5]   1.00-2.00   sec  7.04 MBytes  59.0 Mbits/sec                  
[  5]   2.00-3.00   sec  7.61 MBytes  63.9 Mbits/sec                  
[  5]   3.00-4.00   sec  7.53 MBytes  63.2 Mbits/sec                  
[  5]   4.00-5.00   sec  7.56 MBytes  63.5 Mbits/sec                  
[  5]   5.00-6.00   sec  6.06 MBytes  50.8 Mbits/sec                  
[  5]   6.00-7.00   sec  7.50 MBytes  62.9 Mbits/sec                  
[  5]   7.00-8.00   sec  7.48 MBytes  62.7 Mbits/sec                  
[  5]   8.00-9.00   sec  7.39 MBytes  62.0 Mbits/sec                  
[  5]   9.00-10.00  sec  7.59 MBytes  63.7 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.11  sec   103 MBytes  85.1 Mbits/sec   24             sender
[  5]   0.00-10.00  sec   101 MBytes  84.5 Mbits/sec                  receiver

Quick conclusion: Slow bitrate is only in one direction. Hopefully that is enough to help you know where to start looking. Let me know what specific tests to run.

@WallyZambotti

$ iwconfig

That is a very old unsupported command. Recommend you discontinue use. Tell us what you want to do and we can recommend modern supported commands. You can start with iw.

dubhater commented 1 month ago

@morrownr Something to check is the TX and RX rates in wavemon when you see the low speed with iperf3.

morrownr commented 1 month ago

@dubhater

$ iperf3 -c 192.168.1.1

wavemon shows: rx rate: 86 Mbps, tx rate: 866 Mbps while iperf3 is running.

$ iperf3 -c 192.168.1.1
Connecting to host 192.168.1.1, port 5201
[  5] local 192.168.1.135 port 59808 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  71.1 MBytes   597 Mbits/sec    0    974 KBytes       
[  5]   1.00-2.00   sec  66.2 MBytes   556 Mbits/sec    0    974 KBytes       
[  5]   2.00-3.00   sec  68.8 MBytes   577 Mbits/sec    0    974 KBytes       
[  5]   3.00-4.00   sec  66.2 MBytes   556 Mbits/sec    0    974 KBytes       
[  5]   4.00-5.00   sec  67.5 MBytes   566 Mbits/sec    0    974 KBytes       
[  5]   5.00-6.00   sec  66.2 MBytes   556 Mbits/sec    0    974 KBytes       
[  5]   6.00-7.00   sec  67.5 MBytes   566 Mbits/sec    0    974 KBytes       
[  5]   7.00-8.00   sec  67.5 MBytes   566 Mbits/sec    0    974 KBytes       
[  5]   8.00-9.00   sec  66.2 MBytes   556 Mbits/sec    0    974 KBytes       
[  5]   9.00-10.00  sec  67.5 MBytes   566 Mbits/sec    0    974 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   675 MBytes   566 Mbits/sec    0             sender
[  5]   0.00-10.01  sec   672 MBytes   563 Mbits/sec                  receiver

$ iperf3 -c 192.168.1.1 -R

wavemon shows: rx rate: 19 Mbps, tx rate: 866 Mbps while iperf3 is running.

$ iperf3 -c 192.168.1.1 -R
Connecting to host 192.168.1.1, port 5201
Reverse mode, remote host 192.168.1.1 is sending
[  5] local 192.168.1.135 port 36470 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  28.9 MBytes   243 Mbits/sec                  
[  5]   1.00-2.00   sec  4.91 MBytes  41.2 Mbits/sec                  
[  5]   2.00-3.00   sec  7.07 MBytes  59.3 Mbits/sec                  
[  5]   3.00-4.00   sec  7.51 MBytes  63.0 Mbits/sec                  
[  5]   4.00-5.00   sec  7.49 MBytes  62.8 Mbits/sec                  
[  5]   5.00-6.00   sec  7.52 MBytes  63.1 Mbits/sec                  
[  5]   6.00-7.00   sec  7.66 MBytes  64.3 Mbits/sec                  
[  5]   7.00-8.00   sec  7.40 MBytes  62.1 Mbits/sec                  
[  5]   8.00-9.00   sec  7.63 MBytes  64.0 Mbits/sec                  
[  5]   9.00-10.00  sec  7.59 MBytes  63.6 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  95.0 MBytes  79.7 Mbits/sec  134             sender
[  5]   0.00-10.00  sec  93.7 MBytes  78.6 Mbits/sec                  receiver
Samt43 commented 1 month ago

@morrownr @dubhater : i'm also noticing slow bandwith using 8822bu. Connecting to host 10.0.0.1, port 5201 [ 5] local 100.115.92.198 port 60874 connected to 10.0.0.1 port 5201 [ ID] Interval Transfer Bitrate Retr Cwnd [ 5] 0.00-1.00 sec 6.27 MBytes 52.6 Mbits/sec 3 211 KBytes
[ 5] 1.00-2.00 sec 9.13 MBytes 76.6 Mbits/sec 0 242 KBytes
[ 5] 2.00-3.00 sec 8.82 MBytes 74.0 Mbits/sec 1 266 KBytes
[ 5] 3.00-4.00 sec 8.70 MBytes 73.0 Mbits/sec 0 290 KBytes
[ 5] 4.00-5.00 sec 5.78 MBytes 48.5 Mbits/sec 2 235 KBytes
[ 5] 5.00-6.00 sec 9.13 MBytes 76.6 Mbits/sec 0 264 KBytes
[ 5] 6.00-7.00 sec 9.45 MBytes 79.2 Mbits/sec 0 280 KBytes
[ 5] 7.00-8.03 sec 11.8 MBytes 95.6 Mbits/sec 0 307 KBytes
[ 5] 8.03-9.00 sec 10.9 MBytes 94.3 Mbits/sec 0 334 KBytes
[ 5] 9.00-10.00 sec 10.4 MBytes 87.0 Mbits/sec 2 355 KBytes

[ ID] Interval Transfer Bitrate Retr [ 5] 0.00-10.00 sec 90.3 MBytes 75.8 Mbits/sec 8 sender [ 5] 0.00-10.04 sec 89.7 MBytes 75.0 Mbits/sec receiver

iperf Done.

WallyZambotti commented 1 month ago

Bitrate continues to degrade over time:

$ iw wlxbcec4322ff20 link Connected to 74:83:c2:b5:56:ca (on wlxbcec4322ff20) SSID: TCS freq: 5200 RX: 12596516 bytes (52511 packets) TX: 558933 bytes (3372 packets) signal: -48 dBm rx bitrate: 65.0 MBit/s VHT-MCS 7 VHT-NSS 1 tx bitrate: 135.0 MBit/s VHT-MCS 7 40MHz VHT-NSS 1

bss flags:  short-slot-time
dtim period:    3
beacon int: 100
misha4gps commented 1 month ago

Drivers comparison in AP mode:

88x2bu (morrownr)
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-60.00  sec  1.21 GBytes   173 Mbits/sec                  receiver
iperf3: the client has terminated
-----------------------------------------------------------

rtw_8822bu (lwfinger):
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-30.00  sec   538 MBytes   150 Mbits/sec                  receiver
iperf3: the client has terminated
-----------------------------------------------------------

rtw88_8822bu (kernel)
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-35.00  sec   121 MBytes  29.0 Mbits/sec                  receiver
iperf3: the client has terminated
-----------------------------------------------------------

Hardware: 

Bus 001 Device 004: ID 0bda:b82c Realtek Semiconductor Corp. 802.11ac NIC (rtl8822bu)

Kernel:

Linux Workstation 6.10.0-rc7+ #5 SMP PREEMPT_DYNAMIC Fri Jul 19 20:42:15 EEST 2024 x86_64 x86_64 x86_64 GNU/Linux

Successful test of 802.11r:

88x2bu  - no
rtw_8822bu  - yes
rtw88_8822bu  - yes

Questions:

  1. What is the main reason for the rtw88_8822bu driver being so slow?
  2. Why is the rtw_8822bu driver slower than 88x2bu ?
morrownr commented 1 month ago

@misha4gps

What is the main reason for the rtw88_8822bu driver being so slow?

Probably the following is largely the cause:

[1/4] wifi: rtw88: Init RX burst length for 8822cu/8822bu/8821cu

You can find that patch series at:

https://patchwork.kernel.org/project/linux-wireless/list/

It was sent in yesterday by Dubhater. My opinion is that Realtek did not do a very good job with rtw88 and they included no support for USB. That has all come from the community. By the time we see kernel 6.12 released, you should see better performance with rtw88_8822bu and the other drivers in rtw88.

Why is the rtw_8822bu driver slower than 88x2bu ?

Dubhater can certainly answer this better than me but I'd rather keep him busy prepping patches for upstreaming the numerous patches that need to go upstream such as for the new rtl8821au and rtl8812au drivers. It is a lot of work.

While performance for rtw_8822bu is currently much better than rtw88_8822bu, performance is not symmetrical as shown in the last iperf3 testing I posted above. Why that is is not known to me at this time but if anyone can get to the bottom of it, Dubhater can we need to allow him time to get all of the patches that need to go upstream on their way right now and then we can make a plan and start gathering information. This project covers a lot of drivers and it is complicated work. It will be very nice to see the many patches that are going into 6.12 in place so we can begin the process if depreciating the Reaktek out-of-kernel drivers.

misha4gps commented 1 month ago

@morrownr Thanks for the link and explanation. and many thanks to Dubhater for his efforts in improving the driver

morrownr commented 1 month ago

@misha4gps

Let me make sure I did not mislead you. Any patches that have gone in to go into the kernel are already in this repo. You can look at that patch series right here.

misha4gps commented 1 month ago

@morrownr, I understand this and that is why i did the test.

WallyZambotti commented 1 month ago

Not sure if the following information is at all relevant.

The laptop that I was testing the rtl8822bu just happened to have a PCI rtl8822ce for its Wifi adapter.

When I use iw link it shows the RX bit rate is 175 but the TX bit rate is 600. I would rather that be the other way around but there may be a wider issue with the rtl driver.

henkv1 commented 1 month ago

When I use rtw88 as an AP, my client reports a rx bitrate of 6.0MBit/s, tx bitrate is 390.0 MBit/s. It makes no difference if I use my 8811cu or my 8812bu adapter as AP. My client uses an Intel wireless adapter. The AP is a Raspberry Pi 3b running 64bit Arch.

WallyZambotti commented 1 month ago

From my testing it appears to drop under load. So the bit rate may start at 216 or higher but immediately after placing a load it will drop to 39. And when the load stops the bit rate will rise back up. Even when there is only a load on transmission the RX rate will drop. But only the RX bit rate will change. The TX seems completely steady.

likknb commented 2 weeks ago

yes,help the question please 。rtw88_8822cs According to the same situation

henkv1 commented 2 days ago

The AP usb fixes are now merged into rtw-next (https://github.com/pkshih/rtw.git), so I decided to try the driver that repo. I noticed a huge speed difference between the driver in this repo and the rtw-next version when I put my rtl8811cu device in AP mode (client is Intel wireless):

This repo:

iperf3 -c 192.168.1.120
Connecting to host 192.168.1.120, port 5201
[  5] local 192.168.1.26 port 59940 connected to 192.168.1.120 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  8.00 MBytes  67.0 Mbits/sec    0    124 KBytes       
[  5]   1.00-2.00   sec  7.62 MBytes  64.0 Mbits/sec    0    124 KBytes       
[  5]   2.00-3.00   sec  7.62 MBytes  64.0 Mbits/sec    0    124 KBytes       
[  5]   3.00-4.00   sec  8.25 MBytes  69.2 Mbits/sec    0    124 KBytes       
[  5]   4.00-5.00   sec  8.25 MBytes  69.2 Mbits/sec    0    124 KBytes       
[  5]   5.00-6.00   sec  7.62 MBytes  64.0 Mbits/sec    0    124 KBytes       
[  5]   6.00-7.00   sec  8.25 MBytes  69.2 Mbits/sec    0    124 KBytes       
[  5]   7.00-8.00   sec  7.88 MBytes  66.1 Mbits/sec    0    124 KBytes       
[  5]   8.00-9.00   sec  2.25 MBytes  18.9 Mbits/sec    3    124 KBytes       
[  5]   9.00-10.00  sec  7.88 MBytes  66.0 Mbits/sec    0    124 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  73.6 MBytes  61.8 Mbits/sec    3             sender
[  5]   0.00-10.00  sec  73.1 MBytes  61.3 Mbits/sec                  receiver

iperf3 -R -c 192.168.1.120
Connecting to host 192.168.1.120, port 5201
Reverse mode, remote host 192.168.1.120 is sending
[  5] local 192.168.1.26 port 59148 connected to 192.168.1.120 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec   512 KBytes  4.19 Mbits/sec                  
[  5]   1.00-2.00   sec   512 KBytes  4.19 Mbits/sec                  
[  5]   2.00-3.00   sec   640 KBytes  5.25 Mbits/sec                  
[  5]   3.00-4.00   sec   512 KBytes  4.19 Mbits/sec                  
[  5]   4.00-5.00   sec   512 KBytes  4.19 Mbits/sec                  
[  5]   5.00-6.00   sec   640 KBytes  5.24 Mbits/sec                  
[  5]   6.00-7.00   sec   512 KBytes  4.19 Mbits/sec                  
[  5]   7.00-8.00   sec   512 KBytes  4.19 Mbits/sec                  
[  5]   8.00-9.00   sec   640 KBytes  5.24 Mbits/sec                  
[  5]   9.00-10.00  sec   512 KBytes  4.19 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  6.00 MBytes  5.03 Mbits/sec    0             sender
[  5]   0.00-10.00  sec  5.38 MBytes  4.51 Mbits/sec                  receiver

rtw-next:

iperf3 -c 192.168.1.120
Connecting to host 192.168.1.120, port 5201
[  5] local 192.168.1.26 port 53566 connected to 192.168.1.120 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  13.0 MBytes   109 Mbits/sec    0    126 KBytes       
[  5]   1.00-2.00   sec  17.6 MBytes   148 Mbits/sec    0    126 KBytes       
[  5]   2.00-3.00   sec  21.8 MBytes   182 Mbits/sec    0    126 KBytes       
[  5]   3.00-4.00   sec  22.6 MBytes   190 Mbits/sec    0    126 KBytes       
[  5]   4.00-5.00   sec  21.5 MBytes   180 Mbits/sec    0    126 KBytes       
[  5]   5.00-6.00   sec  22.8 MBytes   191 Mbits/sec    0    126 KBytes       
[  5]   6.00-7.00   sec  23.4 MBytes   196 Mbits/sec    0    126 KBytes       
[  5]   7.00-8.00   sec  22.0 MBytes   185 Mbits/sec    0    126 KBytes       
[  5]   8.00-9.00   sec  22.0 MBytes   185 Mbits/sec    0    126 KBytes       
[  5]   9.00-10.00  sec  23.0 MBytes   193 Mbits/sec    0    126 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   210 MBytes   176 Mbits/sec    0             sender
[  5]   0.00-10.00  sec   209 MBytes   175 Mbits/sec                  receiver

iperf3 -R -c 192.168.1.120
Connecting to host 192.168.1.120, port 5201
Reverse mode, remote host 192.168.1.120 is sending
[  5] local 192.168.1.26 port 44358 connected to 192.168.1.120 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.00   sec  23.6 MBytes   198 Mbits/sec                  
[  5]   1.00-2.00   sec  24.4 MBytes   204 Mbits/sec                  
[  5]   2.00-3.00   sec  24.4 MBytes   204 Mbits/sec                  
[  5]   3.00-4.00   sec  24.6 MBytes   207 Mbits/sec                  
[  5]   4.00-5.00   sec  24.5 MBytes   206 Mbits/sec                  
[  5]   5.00-6.00   sec  24.6 MBytes   207 Mbits/sec                  
[  5]   6.00-7.00   sec  24.4 MBytes   204 Mbits/sec                  
[  5]   7.00-8.00   sec  24.0 MBytes   201 Mbits/sec                  
[  5]   8.00-9.00   sec  24.5 MBytes   206 Mbits/sec                  
[  5]   9.00-10.00  sec  23.6 MBytes   198 Mbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.01  sec   246 MBytes   206 Mbits/sec    0             sender
[  5]   0.00-10.00  sec   243 MBytes   204 Mbits/sec                  receiver

I observe the same when I use my rtl8812bu adapter in AP mode.