Wifi 5g channels incorrect on raspberrypi4 mt7921au

Hardware Questions and Recommendations
1

Hi there!

I am using an raspberrypi4 with fenvi ax1800 (mt7921au chipset) and compiled both latest 23.05-snapshot and 24.10-snapshot.

When I try to setup my wifi in luci for 5GHz band, ax mode its not working great.
When I select channels higher than 44 it jumps up the frequency above 6GHz, not corresponding to the frequency belonging to those channels.

See this picture:

Screenshot from 2024-11-19 16-49-56
Screenshot from 2024-11-19 16-49-56916×647 59.9 KB

I like to have my 5GHz wifi ap on channel 124. Normally that would be 5620MHz but it tries to put it on 6570MHz. And the result is the wifi adapter being disabled.

I already tried upgrading the firmware as told on this page:
https://github.com/morrownr/USB-WiFi/blob/main/home/How_to_Install_Firmware_for_Mediatek_based_USB_WiFi_adapters.md

Does anyone alse has this problem and/or does anyone know how to fix this issue?

2

Also I suspect it has something to do with the mac80211 or hostapp, because the usb wifi module itself is working perfect. When I select channels 36/44 or above 149 (where no radar/dfs check is needed) the right frequency is applied and it all works great.

But for channels between 58 and 149 it raises the frequency far above what it should be according to the channel nr.

In the system logs I see this when trying to put it somewhere in the 58-149 channel range:

Fri Nov 22 02:46:56 2024 daemon.notice netifd: Wireless device 'radio0' is now up
Fri Nov 22 02:46:56 2024 daemon.notice hostapd: phy0-ap0: interface state HT_SCAN->DFS
Fri Nov 22 02:46:56 2024 daemon.notice hostapd: phy0-ap0: DFS-CAC-START freq=5620 chan=124 sec_chan=1, width=1, seg0=122, seg1=0, cac_time=60s
Fri Nov 22 02:46:56 2024 daemon.err hostapd: DFS start_dfs_cac() failed, -1
Fri Nov 22 02:46:56 2024 daemon.err hostapd: Interface initialization failed
Fri Nov 22 02:46:56 2024 daemon.notice hostapd: phy0-ap0: interface state DFS->DISABLED
Fri Nov 22 02:46:56 2024 daemon.notice hostapd: phy0-ap0: AP-DISABLED

Does anyone know how to fix this?

3

https://w1.fi/cgit/hostap/tree/hostapd/hostapd.conf#n219

1 Like
4

May I ask why you chose a snapshot over the known working 23.5.05?

It changes the tone of the thread if you are, intentionally, running bleeding edge.

And may I ask:

Please connect to your OpenWrt device using ssh and copy the output of the following commands and post it here using the "Preformatted text </> " button:
grafik
Remember to redact passwords, MAC addresses and any public IP addresses you may have:

ubus call system board
cat /etc/config/network
cat /etc/config/wireless
cat /etc/config/dhcp
cat /etc/config/firewall
5

To be fair, mt7921au support needs rather recent mt76 (around >=v6.2) drivers, so snapshots do make sense for this hardware.

Yes, mt76 support has been backported to the openwrt-23.05 and should be good enough in 23.05.5, but at least 23.05.0 was not quite up to it for mt7921au.

6

First, thanks for your reaction, guys!

Yeah, I like to compile latest snapshots for my devices. Its just a habit :slight_smile: To see what has changed and see if it performs better. I like to try out new versions of drivers.

@brada4
Brada, you posted a link of hostapd.conf. I saw the DFS_CAC lines. What should I do with the information?

In the 23-snapshot buildroot I looked up the file and uncommented that DFS_CAC line that you pointed out in hostapd.conf file. Compiled the firmware, upgraded the firmware file to the router but still having the same issue.
(I did a make distclean beforehand, to make sure old configs and compiled binaries were truelly gone)

On the router via uart connection shell I edited /run/hostapd-phy0.conf to add the "acs_exclude_dfs=1" line, but the file gets auto updated I think and the line was removed again.
So I am wondering what to do with the "acs_exclude_dfs=1" line, where to put it.

@LilRedDog
I doubt the issue lies anywhere else than drivers, mt76, mt7921au, nl80211, hostapd, or its related configs. Network/dhcp/firewall is performing fine.

But okido, here we go! :slight_smile:

ubus call system board:

{
        "kernel": "6.6.61",
        "hostname": "RaspberryPI4b",
        "system": "ARMv8 Processor rev 3",
        "model": "Raspberry Pi 4 Model B Rev 1.4",
        "board_name": "raspberrypi,4-model-b",
        "rootfs_type": "squashfs",
        "release": {
                "distribution": "OpenWrt",
                "version": "SNAPSHOT",
                "revision": "r28146-52b6c92479",
                "target": "bcm27xx/bcm2711",
                "description": "OpenWrt SNAPSHOT r28146-52b6c92479",
                "builddate": "1732223081"
        }
}

cat /etc/config/network:

config interface 'loopback'
        option device 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config globals 'globals'
        option ula_prefix 'fdfd:4fa3:5ab8::/48'

config device
        option name 'br-lan'
        option type 'bridge'
        option ipv6 '0'
        option igmp_snooping '1'
        list ports 'eth0'

config interface 'lan'
        option device 'br-lan'
        option proto 'static'
        option ipaddr '192.168.1.254'
        option netmask '255.255.255.0'
        option delegate '0'
        option ip6assign '60'

config device
        option name 'eth0'
        option ipv6 '0'

config interface 'Surf_OVPN'
        option proto 'none'
        option device 'tun0'
        option delegate '0'
        option auto '0'

config interface 'Surfshark'
        option proto 'wireguard'
        option private_key 'xxxxxxxxxxxx'
        list addresses '10.14.0.2/16'
        list dns '162.252.172.57'
        list dns '149.154.159.92'
        option delegate '0'
        option auto '0'

config wireguard_Surfshark
        option description 'nl-ams.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option endpoint_host 'nl-ams.prod.surfshark.com'
        option endpoint_port '51820'
        option route_allowed_ips '1'

config wireguard_Surfshark
        option description 'de-fra.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'de-fra.prod.surfshark.com'
        option endpoint_port '51820'
        option disabled '1'

config wireguard_Surfshark
        option disabled '1'
        option description 'de-ber.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'de-ber.prod.surfshark.com'
        option endpoint_port '51820'

config wireguard_Surfshark
        option description 'uk-lon.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'uk-lon.prod.surfshark.com'
        option endpoint_port '51820'
        option disabled '1'

config wireguard_Surfshark
        option description 'uk-man.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'uk-man.prod.surfshark.com'
        option endpoint_port '51820'
        option disabled '1'

config wireguard_Surfshark
        option description 'be-bru.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'be-bru.prod.surfshark.com'
        option endpoint_port '51820'
        option disabled '1'

config wireguard_Surfshark
        option description 'be-anr.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'be-anr.prod.surfshark.com'
        option endpoint_port '51820'
        option disabled '1'

config wireguard_Surfshark
        option description 'ch-zur.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'ch-zur.prod.surfshark.com'
        option endpoint_port '51820'
        option disabled '1'

config wireguard_Surfshark
        option description 'us-nyc.prod.surfshark.com'
        option public_key 'xxxxxxxxxxxxxxxxxxxxxxxxx'
        list allowed_ips '0.0.0.0/0'
        option route_allowed_ips '1'
        option endpoint_host 'us-nyc.prod.surfshark.com'
        option endpoint_port '51820'
        option disabled '1'

config interface 'wan'
        option proto 'pppoe'
        option device 'eth1.6'
        option username 'xxxxxxxxx'
        option password 'xxxxxxxxxxx'
        option ipv6 '0'
        option sourcefilter '0'
        option delegate '0'

config device
        option type '8021q'
        option ifname 'eth1'
        option vid '6'
        option name 'eth1.6'
        option ipv6 '0'

config device
        option name 'pppoe-wan'
        option ipv6 '0'

config device
        option name 'eth1'
        option ipv6 '0'

/etc/config/wireless:

config wifi-device 'radio0'
        option type 'mac80211'
        option path 'scb/fd500000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0/usb1/1-1/1-1.3/1-1.3:1.0'
        option band '5g'
        option channel '124'
        option cell_density '0'
        option country 'NL'
        option htmode 'HE80'

config wifi-iface 'default_radio0'
        option device 'radio0'
        option network 'lan'
        option mode 'ap'
        option ssid 'The Kingdom Gods_5G'
        option encryption 'sae'
        option key 'xxxxxxxxxxxx'
        option isolate '1'
        option wpa_disable_eapol_key_retries '1'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        list maclist 'xxxxxxxxxxxxxxxxxx'
        option ocv '0'

cat /etc/config/dhcp:

config dnsmasq
        option domainneeded '1'
        option boguspriv '1'
        option filterwin2k '0'
        option localise_queries '1'
        option rebind_protection '1'
        option rebind_localhost '1'
        option local '/lan/'
        option domain 'lan'
        option expandhosts '1'
        option nonegcache '0'
        option cachesize '1000'
        option authoritative '1'
        option readethers '1'
        option leasefile '/tmp/dhcp.leases'
        option resolvfile '/tmp/resolv.conf.d/resolv.conf.auto'
        option nonwildcard '1'
        option localservice '1'
        option ednspacket_max '1232'
        option filter_aaaa '0'
        option filter_a '0'

config dhcp 'lan'
        option interface 'lan'
        option start '100'
        option limit '150'
        option leasetime '12h'
        option dhcpv4 'server'

config odhcpd 'odhcpd'
        option maindhcp '0'
        option leasefile '/tmp/hosts/odhcpd'
        option leasetrigger '/usr/sbin/odhcpd-update'
        option loglevel '4'

config host
        option name 'Goliath'
        option dns '1'
        option ip '192.168.1.10'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'

config host
        option name 'Galaxy-S7-Edge'
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.11'

config host
        option name 'Meta-Quest-2'
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.12'

config host
        option name 'Rasberry-PI4-wifi'
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.14'

config host
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.15'
        option name 'Samsung-TV'

config host
        option name 'Osprey'
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.18'

config host
        option name 'Squid'
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.19'

config host
        option name 'Jaguar'
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.20'

config host
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.21'
        option name 'GL-MT300N-V2-1'

config host
        option dns '1'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.22'
        option name 'GL-MT300N-V2-2'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.50'
        option name 'Echo-Dot-4'
        option dns '1'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.51'
        option name 'Echo-Dot-4-Second'
        option dns '1'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option ip '192.168.1.52'
        option name 'Echo-Dot-3'
        option dns '1'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Couch-RGB-L'
        option dns '1'
        option ip '192.168.1.60'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Couch-RGB-R'
        option dns '1'
        option ip '192.168.1.61'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Bed-Light-RGB'
        option dns '1'
        option ip '192.168.1.62'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Ceiling-RGB'
        option dns '1'
        option ip '192.168.1.70'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Ceiling-RGB-Kitchen'
        option dns '1'
        option ip '192.168.1.71'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Ceiling-RGB-PC'
        option dns '1'
        option ip '192.168.1.72'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Ceiling-RGB-Bedroom'
        option dns '1'
        option ip '192.168.1.73'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Smart-Switch-1-AirPurifier'
        option dns '1'
        option ip '192.168.1.80'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Smart-Switch-2-CV'
        option dns '1'
        option ip '192.168.1.81'

config host
        list mac 'xxxxxxxxxxxxxxxxxxxxx'
        option name 'Smart-Switch-3-BED'
        option dns '1'
        option ip '192.168.1.82'

config host
        option name 'papa-ipad'
        list mac 'xxxxxxxxxxxxxxxxxxxxx'

cat /etc/config/firewall:

config defaults
        option input 'DROP'
        option output 'ACCEPT'
        option forward 'DROP'
        option synflood_protect '1'
        option drop_invalid '1'

config zone
        option name 'lan'
        option input 'ACCEPT'
        option output 'ACCEPT'
        option forward 'ACCEPT'
        list network 'lan'

config zone
        option name 'wan'
        option input 'DROP'
        option output 'ACCEPT'
        option forward 'DROP'
        option masq '1'
        option mtu_fix '1'
        list network 'wan6'
        list network 'wan'

config forwarding
        option src 'lan'
        option dest 'wan'

config rule
        option name 'Allow-DHCP-Renew'
        option src 'wan'
        option proto 'udp'
        option dest_port '68'
        option target 'ACCEPT'
        option family 'ipv4'
        option enabled '0'
        option limit '1000/second'

config rule
        option name 'Allow-Ping'
        option src 'wan'
        option proto 'icmp'
        option family 'ipv4'
        option target 'ACCEPT'
        option enabled '0'
        list icmp_type 'echo-request'
        option limit '1000/second'

config rule
        option name 'Allow-IGMP'
        option src 'wan'
        option proto 'igmp'
        option family 'ipv4'
        option target 'ACCEPT'
        option enabled '0'
        option limit '1000/second'

config rule
        option name 'Allow-DHCPv6'
        option src 'wan'
        option proto 'udp'
        option dest_port '546'
        option family 'ipv6'
        option target 'ACCEPT'
        option enabled '0'
        option limit '1000/second'

config rule
        option name 'Allow-MLD'
        option src 'wan'
        option proto 'icmp'
        option family 'ipv6'
        option target 'ACCEPT'
        option enabled '0'
        list src_ip 'fe80::/10'
        option limit '1000/second'

config rule
        option name 'Allow-ICMPv6-Input'
        option src 'wan'
        option proto 'icmp'
        list icmp_type 'echo-request'
        list icmp_type 'echo-reply'
        list icmp_type 'destination-unreachable'
        list icmp_type 'packet-too-big'
        list icmp_type 'time-exceeded'
        list icmp_type 'bad-header'
        list icmp_type 'unknown-header-type'
        list icmp_type 'router-solicitation'
        list icmp_type 'neighbour-solicitation'
        list icmp_type 'router-advertisement'
        list icmp_type 'neighbour-advertisement'
        option limit '1000/sec'
        option family 'ipv6'
        option target 'ACCEPT'
        option enabled '0'

config rule
        option name 'Allow-ICMPv6-Forward'
        option src 'wan'
        option dest '*'
        option proto 'icmp'
        option limit '1000/sec'
        option family 'ipv6'
        option target 'ACCEPT'
        option enabled '0'
        list icmp_type 'bad-header'
        list icmp_type 'destination-unreachable'
        list icmp_type 'echo-reply'
        list icmp_type 'echo-request'
        list icmp_type 'packet-too-big'
        list icmp_type 'time-exceeded'
        list icmp_type 'unknown-header-type'

config rule
        option name 'Allow-IPSec-ESP'
        option src 'wan'
        option dest 'lan'
        option proto 'esp'
        option target 'ACCEPT'
        option enabled '0'
        option limit '1000/second'

config rule
        option name 'Allow-ISAKMP'
        option src 'wan'
        option dest 'lan'
        option dest_port '500'
        option proto 'udp'
        option target 'ACCEPT'
        option enabled '0'
        option limit '1000/second'

config zone
        option name 'openvpn'
        option input 'DROP'
        option output 'ACCEPT'
        option forward 'DROP'
        option masq '1'
        option mtu_fix '1'
        list network 'Surf_OVPN'

config zone
        option name 'wireguard'
        option input 'DROP'
        option output 'ACCEPT'
        option forward 'DROP'
        option masq '1'
        option mtu_fix '1'
        list network 'Surfshark'

config forwarding
        option src 'lan'
        option dest 'openvpn'

config forwarding
        option src 'lan'
        option dest 'wireguard'

and the error in syslog:

Fri Nov 22 21:34:40 2024 daemon.notice hostapd: phy0-ap0: interface state HT_SCAN->DFS
Fri Nov 22 21:34:40 2024 daemon.notice hostapd: phy0-ap0: DFS-CAC-START freq=5620 chan=124 sec_chan=-1, width=1, seg0=106, seg1=0, cac_time=60s
Fri Nov 22 21:34:40 2024 daemon.err hostapd: DFS start_dfs_cac() failed, -1
Fri Nov 22 21:34:40 2024 daemon.err hostapd: Interface initialization failed
Fri Nov 22 21:34:40 2024 daemon.notice hostapd: phy0-ap0: interface state DFS->DISABLED
Fri Nov 22 21:34:40 2024 daemon.notice hostapd: phy0-ap0: AP-DISABLED

I think that looking up whats going on with radar check DFS_CAC in drivers or hostapd source or config file is the best bet. But I wonder if I have to change it in buildroot of 23-snapshot or that I can for example have to edit config files like /etc/wireless (or other file) on the router itself.

7

https://github.com/morrownr/USB-WiFi/issues/107

Here I found something about mt7921au driver bug, DFS not working.

Bug: AP Mode DFS (5 GHz) support is non-functional
Status: open

Reported by @morrownr
Confirmed by numerous users.

This is really a serious omission in that in many places in the world there are limited non-DFS channels available leading to high levels of congestion.

Dear Mediatek, does your usb chipset competitor support DFS channels in AP Mode? Yes they do. See: out-of-kernel drivers for rtl8812au, rtl8811au, rtl8812bu and rtl8811cu. You need to think about this. Sincerely.

Unless the linux drivers have been updated to support DFS, this seems to be an unfixable issue for the time being (for me atleast).

8

Disabling dfs channels fixes ACS. Caps are wrong that dfs survey fails dead.

1 Like
9

Okay, what do I do to disable the DFS channels? Like what file do I have to modify?
Is it "openwrt-23.05-k6.6.61-23-11-2024/build_dir/target-aarch64_cortex-a72_musl/hostapd-wpad-basic-mbedtls/hostapd-2024.09.15~5ace39b0/hostapd/hostapd.conf" ?

10

I'd forgotten about that... :neutral_face:

Manually pick a non DFS channel and, depending on your country, you may not have 80MHz of DFS free space; limiting your bandwidth.

11

Personally I never use DFS channels to avoid interruptions, so yeah.....though I own the same MT7921AU I never noticed this problem :slight_smile: