AP mode issues go here

[morrownr]

I am currently testing band 1, 2.4 GHz, AP mode.

I found that I needed a modification to the ht_capab line as used in hostapd.conf. The example is shown in 8812au.conf and my AP guide on the Main Menu. I will be updating the docs to show the change.

Iperf3 results:

$ iperf3 -c 192.168.1.24
Connecting to host 192.168.1.24, port 5201
[  5] local 192.168.1.127 port 56644 connected to 192.168.1.24 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  12.2 MBytes   102 Mbits/sec    0    570 KBytes       
[  5]   1.00-2.00   sec  10.7 MBytes  89.7 Mbits/sec    0    672 KBytes       
[  5]   2.00-3.00   sec  11.2 MBytes  94.4 Mbits/sec    0    717 KBytes       
[  5]   3.00-4.00   sec  10.0 MBytes  83.9 Mbits/sec    0    757 KBytes       
[  5]   4.00-5.00   sec  10.0 MBytes  83.9 Mbits/sec    0    800 KBytes       
[  5]   5.00-6.00   sec  8.75 MBytes  73.4 Mbits/sec    0    891 KBytes       
[  5]   6.00-7.00   sec  11.2 MBytes  94.4 Mbits/sec    0    988 KBytes       
[  5]   7.00-8.00   sec  11.2 MBytes  94.4 Mbits/sec    0   1.08 MBytes       
[  5]   8.00-9.00   sec  11.2 MBytes  94.4 Mbits/sec    0   1.08 MBytes       
[  5]   9.00-10.00  sec  11.2 MBytes  94.4 Mbits/sec    0   1.08 MBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   108 MBytes  90.5 Mbits/sec    0             sender
[  5]   0.00-10.01  sec   104 MBytes  87.4 Mbits/sec                  receiver

iperf Done.

The results are good for a 20 MHz channel width test on an AC1200 adapter. I will be running my main system in this AP for several days to see if anything comes up. If things test good, I will move to Band 2 (5 GHz) next.

[morrownr]

Test results for 5 GHZ AP mode:

Channel: 100 (DFS) others tested also
Hardware: RasPi4B
Distro: RasPiOS 2023-12-05
Guide: USB-WiFi AP Guide
hostapd settings:
ht_capab=[HT40+][HT40-][SHORT-GI-20][SHORT-GI-40][MAX-AMSDU-7935]
vht_capab=[MAX-MPDU-11454][SHORT-GI-80][TX-STBC-2BY1][RX-STBC-1][HTC-VHT][MAX-A-MPDU-LEN-EXP7]
8812au.conf:
options 8812au rtw_switch_usb_mode=1 rtw_vht_enable=2 rtw_dfs_region_domain=1 rtw_country_code=US

$ iw dev
phy#0
	Interface wlan0
		ifindex 4
		wdev 0x1
		addr 00:c0:ca:aa:e8:ba
		ssid myPI-WiFi5
		type AP
		channel 100 (5500 MHz), width: 80 MHz, center1: 5530 MHz
		txpower 14.00 dBm

$ iperf3 -c 192.168.1.1
Connecting to host 192.168.1.1, port 5201
[  5] local 192.168.1.127 port 34846 connected to 192.168.1.1 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  51.6 MBytes   433 Mbits/sec    0   1011 KBytes       
[  5]   1.00-2.00   sec  51.2 MBytes   430 Mbits/sec    0   1011 KBytes       
[  5]   2.00-3.00   sec  51.2 MBytes   430 Mbits/sec    0   1011 KBytes       
[  5]   3.00-4.00   sec  50.0 MBytes   419 Mbits/sec    0   1011 KBytes       
[  5]   4.00-5.00   sec  51.2 MBytes   430 Mbits/sec    0   1011 KBytes       
[  5]   5.00-6.00   sec  51.2 MBytes   430 Mbits/sec    0   1011 KBytes       
[  5]   6.00-7.00   sec  51.2 MBytes   430 Mbits/sec    0   1011 KBytes       
[  5]   7.00-8.00   sec  50.0 MBytes   419 Mbits/sec    0   1011 KBytes       
[  5]   8.00-9.00   sec  51.2 MBytes   430 Mbits/sec    0   1011 KBytes       
[  5]   9.00-10.00  sec  51.2 MBytes   430 Mbits/sec    0    742 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   510 MBytes   428 Mbits/sec    0             sender
[  5]   0.00-10.00  sec   507 MBytes   425 Mbits/sec                  receiver

iperf Done.

Thoughts: Looks good. I will now do a long term test using it as my main AP for the next 2 weeks or so. Note that I am running it on a DFS channel. This driver is one of the few that supports DFS channels in AP mode.

Please report your results.

@morrownr

[morrownr]

I have completed a longer term test on both bands and am not seeing any problems. My opinion is that this driver/chipset combination is exceptionally good for AP mode. I consider it to be as stable as the mt7612u driver/chipset in AP mode and this driver can do DFS channels in AP mode which the mt7612u cannot without modifying the driver source. This driver/chipset is more stable than the rtl8812bu in AP mode.

Let me know if you find any AP mode related problems.

@morrownr

[lwfinger]

If you have a patch for DFS channels in AP mode for mt7612u, please push is upstream to wireless-next@vger.kernel.org. That way the rest of the community can benefit from your experience,

If you need any help in preparing a kernel patch, I am happy to help.

[morrownr]

@lwfinger

Larry,

If you have a patch for DFS channels in AP mode for mt7612u, please push is upstream to wireless-next@vger.kernel.org. That way the rest of the community can benefit from your experience,

I did not develop the patch. In fact, it has been submitted to OpenWRT's mt76 repo which is a downstream of the mt76 driver and it is manned by Mediatek devs:

openwrt/mt76#428

The Mediatek devs won't take the patch. My theory is that Mediatek did not get the extra certification that is required for AP mode DFS support. It would not surprise me if Realtek did not get it either but the support is there.

If you need any help in preparing a kernel patch, I am happy to help.

I appreciate the offer and will contact you directly since my need for help is off topic here. I do need to submit a patch for RTW88 for the 8821CU driver.

Thanks,

@morrownr

[morrownr]

Updated report: I have continued to test AP mode with this driver. The driver is used on a RasPi4B using RasPiOS 12-05-2023 and the setup is using my Bridged Wireless Access Point guide as shown on the Main Menu of this site. The tested adapter is an Alfa ACH.

I rate the stability and performance of this driver in AP mode to be excellent and its support for DFS channels in AP mode make the rtl8812au chipset/driver combination a desirable setup for those using AP mode.

It is time for me to move on to other tests. If you see an AP mode issue, please post.

@morrownr