HT40 configured, but android-apps say 20MHz

Installing and Using OpenWrt
1

I wonder why my android app says width 20MHz.

root@C7v5-S0:~# ubus call system board
{
	"kernel": "5.15.137",
	"hostname": "C7v5-S0",
	"system": "Qualcomm Atheros QCA956X ver 1 rev 0",
	"model": "TP-Link Archer C7 v5",
	"board_name": "tplink,archer-c7-v5",
	"rootfs_type": "squashfs",
	"release": {
		"distribution": "OpenWrt",
		"version": "23.05.2",
		"revision": "r23630-842932a63d",
		"target": "ath79/generic",
		"description": "OpenWrt 23.05.2 r23630-842932a63d"
	}
}

root@C7v5-S0:~# cat /etc/config/wireless 

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'pci0000:00/0000:00:00.0'
	option channel '36'
	option band '5g'
	option htmode 'VHT80'
	option disabled '1'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'bed0.5-mix'
	option encryption 'sae-mixed'
	option key '...'

config wifi-device 'radio1'
	option type 'mac80211'
	option path 'platform/ahb/18100000.wmac'
	option channel '11'
	option band '2g'
	option htmode 'HT40'
	option country 'AT'
	option cell_density '0'

config wifi-iface 'default_radio1'
	option device 'radio1'
	option network 'lan'
	option mode 'ap'
	option ssid 'bed0.4-2'
	option encryption 'psk2'
	option key '...'

config wifi-iface 'wpa3_radio1'
	option device 'radio1'
	option network 'lan'
	option mode 'ap'
	option ssid 'bed0.4-mix'
	option encryption 'sae-mixed'
	option key '...'
	option disabled '1'
2

Try channel set to auto.

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3

Also, be sure your phone's wifi chipset actually supports 40MHz connectivity. If you have an older or more budget-oriented phone, the wifi chipset may be limited.

3 Likes
4

Changed to channel 6, but 20 MHz.

No idea. With 5 GHz it shows 80MHz. What I noticed, that changing to 40MHz showed a stronger signal, but 20MHz was displayed.

Is there a terminal command, which I can use with another openwrt device?

5

Wait, you're referring to 2.4 GHz?

There are only three 20 MHz non-overlapping channels on the 2.4 GHz WiFi band. Except in rural locations, usually you'll only get 20 MHz unless ~1/3 of the band is [completely] free.

There's an extended discussion on this in the quoted thread.

No, you cannot force a client to change from 20 MHz to 40 MHz bandwidth via CLI.

2 Likes
6

I was asking because:

In the meantime I know, my phone can show 40MHz, I see it with foreign neighbour networks.

I was asking for a command which displays the width of the wifi-networks.

ht40
ht40864×705 80.5 KB

Here you see 40MHz overlapped, but ok, if it doesn't work here I know now, I did not do a misconfiguration. It didn't work here with channel 6 and 11.

7

Did you review the discussion in the linked thread?

In your case, I'm not sure what the screenshot shows.

The width of wifi-networks - can you be more specific with what you're asking?

On the OpenWrt; on the phone?

I'm not understanding your statement:

  • To be clear, we are discussing these radios, correct?
  • We agree 2 cora's and 3 other SSIDs use "3 @ 40MHz" and channels 1 and 6
  • and cablelink and another (I assume no SSID?) uses 11

I don't see space in the band for your "bed" SSIDs to Tx @ 40 MHz.

Edit, I know we're discussing the phone, I should more clearly say:

"I don't see space on the band for your phone to transmit at 40Mhz bandwidth to the 'bed' SSIDs on radio1"

8

Did you check the button?

or

option noscan '1'

I don't see it in your config.

:warning: Turning this on will violate regulatory requirements!

~From: https://openwrt.org/docs/guide-user/network/wifi/basic#mac80211_options

9

Of course, but I am not sure, if I did understand everything. In short, if it doesn't work, you can do nothing against it.

Simply that what I see with my mobile phone, 20 / 40 / 80 MHz

On my pc, there is:

nmcli -f ALL dev wifi

or

iwlist wlp2s0 scan

But both don't show the width. So I am searching a command in an openwrt terminal which lists the SSID with the width.

In the mentioned thread

I think in my screenshot the band is not clear, but there is 40MHz, so I am wondering why it is working with the neighbours.

Ok, I am wondering why the mobile phone shows a stronger signal when set to HT40.

I wanted to know if I configured something wrong, if not, I am happy :wink:

1 Like
10

screen648
screen648722×63 7.84 KB

:warning: I assume you're operating the AP in a Faraday Cage, this is a theoretical inquiry, or other situation where the radio regulations don't apply, etc. Please follow the Community Guidelines .

  • They could have and old AP
  • Maybe you have an old AP :wink:

EDIT:

Maybe you have an old phone? :thinking:

You have working cell phone that is 15+ years old? :open_mouth:

11

Did you try Channel 1 or 3 (Wikipedia says 3)?

That has to be the free [20MHz] Channel for 40MHz to work as your cora example.

To be be clear, "the space that covers 1 and 6". :spiral_notepad: I mean non-overlapping.

In laymans terms, "set the channel as if you referencing its 20MHz fallback channel. I'll show a screenshot from an app that illustrates this (please understand I cannot use a live 2.4 GHz example):

Screenshot_20231211-053512_WiFiAnalyzer

See: https://en.wikipedia.org/wiki/List_of_WLAN_channels#2.4_GHz_(IEEE_802.11b-1999|802.11b/IEEE_802.11g-2003|g/IEEE_802.11n-2009|n/Wi-Fi_6|ax)

In other words, the only 40 MHz space in your screenshot - is to share with cora (hence more interference on the band). I don't think this will work.

12

Both didn't help.

option noscan '1'

was the solution with channel 3, but now I am mainly influencing my own ssids. I have 1 at ch1, 1 at ch6 and 2 at ch11.

So forget it, I am going back to 20MHz.

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13

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