Get the full speed out of ALFA AWUS036ACHM in AP mode

[frogro]

Hi Nick,
I bought the ALFA AWUS036ACHM based on your recommendation and use it on a Pi 4 in AP mode. You gave the hint: One thing to consider regarding 5 GHz AP mode is that this is an AC600 device so maximum transfer rate is limited to 433 Mb/s. I am wondering how to get full speed out of it. When I connect it to my phone or laptop the transfer rate seems to be limited to 65 Mbps with 5 GHz AC. What do I get wrong? Is there a way to get more out of it by optimzing hostadp.conf or other settings?
Cheers, Frank

[morrownr]

Hi Frank,

Is there a way to get more out of it by optimzing hostadp.conf or other settings?

We likely can get it up to top performance. Do you know what iperf3 is? The reason I ask is that we first need to get something set up so that can reliably see what we are getting for throughput.

Another thing we need to look at is the details of the setup on the Pi4B. What OS are you running? Are you running hostapd?

If running hostapd, post the contents of your hostapd.conf file?

[frogro]

Hi Nick,
Thanks for your quick reply and support. Unfortunately I have never heard about iperf3.
This is the content of my (in general working) hostadp.conf:
driver=nl80211
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
beacon_int=100
auth_algs=1
wpa_key_mgmt=WPA-PSK
ssid=raspi-webgui
hw_mode=a
channel=36
#ieee80211d=1
ieee80211ac=1
ieee80211n=1
wmm_enabled=1
wpa_passphrase=ChangeMe
interface=wlan1
wpa=2
wpa_pairwise=CCMP
country_code=DE

......
The ALFA USB wifi dongle is set on wlan1 as an Wifi AP/Hotspot. My configuration works with and without bridged internet by any source (LAN, WLAN (on RP internal adapter) or USB tethering from my Android device.
Maybe you can help me to improve the speed.
Cheers, Frank

[morrownr]

Frank,

I just hooked my ACHM up to my main amd64 dev box. It is two walls away from the WiFi router that it is connecting to so this test result is not from a same room test. Here is the iperf3 result:

$ iperf3 -c 192.168.1.1
Connecting to host 192.168.1.1, port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  23.5 MBytes   197 Mbits/sec    0    369 KBytes       
[  5]   1.00-2.00   sec  22.3 MBytes   187 Mbits/sec    0    464 KBytes       
[  5]   2.00-3.00   sec  22.7 MBytes   190 Mbits/sec    0    485 KBytes       
[  5]   3.00-4.00   sec  21.9 MBytes   183 Mbits/sec    0    485 KBytes       
[  5]   4.00-5.00   sec  22.7 MBytes   191 Mbits/sec    0    485 KBytes       
[  5]   5.00-6.00   sec  21.7 MBytes   182 Mbits/sec    0    485 KBytes       
[  5]   6.00-7.00   sec  21.8 MBytes   183 Mbits/sec    0    485 KBytes       
[  5]   7.00-8.00   sec  22.8 MBytes   191 Mbits/sec    0    485 KBytes       
[  5]   8.00-9.00   sec  22.2 MBytes   187 Mbits/sec    0    512 KBytes       
[  5]   9.00-10.00  sec  22.5 MBytes   189 Mbits/sec    0    512 KBytes       

[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   224 MBytes   188 Mbits/sec    0             sender
[  5]   0.00-10.01  sec   222 MBytes   186 Mbits/sec                  receiver

So we are seeing an average of about 187 Mb/s. Is that good, bad or something else? With a USB2, AC600 adapter, we can see up to link rates of 434 Mb/s. Given that this technology is half duplex, we should see maximum throughput of about half of that number which should be around 217. That is a perfect world number. If we throw in congestion from other wifi devices on the same channel and a few walls plus some distance, thoughput will fall off. Actually, with the ACHM. the falloff from distance and walls is fall less than many other adapters. In fact, I can set up a test situation where this adapter can smoke AC1200 adapters. The reason is the superior range of this adapter.

Now, let's look closer at the iperf3 results above. A solid 187 Mb/s from an AC600 adapter working through two walls in really good. Basically you can think of it like this: Unless you have internet access that has a speed in excess of 200 Mb/s then this adapter is not going to slow things down.

Regards

[morrownr]

Let's work on the hostapd.conf first. I took your hostapd.conf and added a few things and changed the order to group like things in the order I am used to. It should be a drop in replacement. The old hostapd.conf was probably only alllowing a link speed of 87 Mb/s and there were probably security issues. Hopefully this will get you up a max link speed of 434. Let me know.

ssid=raspi-webgui
country_code=DE
driver=nl80211
ctrl_interface=/var/run/hostapd
ctrl_interface_group=0
interface=wlan1
beacon_int=100

# Security
wpa_passphrase=ChangeMe
wpa=2
auth_algs=1
wpa_key_mgmt=WPA-PSK
wpa_pairwise=CCMP
rsn_pairwise=CCMP

hw_mode=a
# Channel
channel=36
# Channel width
vht_oper_chwidth=1
# VHT center channel (chan + 6)
vht_oper_centr_freq_seg0_idx=42

#ieee80211d=1

ieee80211n=1
wmm_enabled=1
# mt7610u
ht_capab=[HT40+][HT40-][GF][SHORT-GI-20][SHORT-GI-40]

ieee80211ac=1
# mt7610u
vht_capab=[SHORT-GI-80][MAX-A-MPDU-LEN-EXP3][RX-ANTENNA-PATTERN][TX-ANTENNA-PATTERN]

[frogro]

Thx Nick. Full speed is reached! You genius!

[frogro]

Hi Nick, I also tried to connect a Hotspot in Ap mode with the ALFA on my Ubuntu Studio tablet. It is quite easy to create a Hotspot in the WiFi / network settings. But Ubuntu does not use hostapd, as far as I can see. Is there a way to get full speed out of the ALFA under Ubuntu, too?

[frogro]

I just can choose band (A 5GHz), chanel (36), MTU (automatic). No idea if I need to change the proxy method (automatic) or IP4 settings...

[samthelion17]

Can I use this config for other WiFi adapters? I want to use the internal adapter of my Lenovo Thinkcentre m715q, lspci says it's a Qualcomm Atheros QCA6174 802.11ac Wireless Network Adapter.

[morrownr]

Hi @samthelion17

Can I use this config for other WiFi adapters?

Maybe. Maybe not. We would need to know the capabilities of your wifi card.

Recommend you start a new issue/discussion and give details of what you are trying to accomplish and then I can go over how you determine the capabilities of your card.

@morrownr

[morrownr]

I am not familiar with how Ubuntu does the Hotspot. I have used it but have not explored how it works. I am pretty sure that they are using very generic settings that will not provide maximum performance. You might get faster answers over at:

https://ubuntuforums.org/

... in the Networking and Wireless forum.

[frogro]

Hi Nick
it's once again me, Frank. Could it be that with the configuration you send me the Alfa only provides a 5Ghz AP and so an ESP8266 cannot connect? If so, could you add the required lines for a 2.4 GHz connection, too?
Cheers Frank

[morrownr]

What's up Frank?

Could it be that with the configuration you send me the Alfa only provides a 5Ghz AP

That is exactly what it could be.

so an ESP8266 cannot connect?

I don't know what that is.

could you add the required lines for a 2.4 GHz connection, too?

I certainly can add the required lines for a 2.4 GHz connection but first you need another wifi adapter and another hostapd.conf file.

USB WiFi adapters contain only one radio. To have dual band, you need two radios. WiFi routers that support 5 GHz and 2.4 GHz have two radios inside.. Here is a link to a guide that I have available:

https://github.com/morrownr/7612u/blob/main/Bridged_Wireless_Access_Point.md