Only 5 GHz Wi-Fi Radio Visible After Fresh Install

MicroMan · May 30, 2025, 11:04am

I've tried reinstalling OpenWRT on my Raspberry Pi 4 several times, but I can only see the 5 GHz radio. According to my knowledge, the Raspberry Pi 4 supports dual-band Wi-Fi (2.4 GHz and 5 GHz), but even after a clean install, only the 5 GHz network is available. What could be causing this issue?

brada4 · May 30, 2025, 4:12pm

It is single radio, you choose the band it operates, it is not both bands. You can add old wifi4 usb adapter to serve the rest.

LilRedDog · May 30, 2025, 4:26pm

See it 'where'?

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:

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

Let's see if the SD card is actually overwriting the install.

MicroMan · May 30, 2025, 5:39pm

vi /etc/config/wireless

config wifi-device 'radio0'
        option type 'mac80211'
        option path 'platform/soc/fe300000.mmcnr/mmc_host/mmc1/mmc1:0001/mmc1:00
        option band '5g'
        option channel '36'
        option htmode 'VHT80'
        option disabled '1'

config wifi-iface 'default_radio0'
        option device 'radio0'
        option network 'lan'
        option mode 'ap'
        option ssid 'OpenWrt'
        option encryption 'none'

~
~
~
~

oot@OpenWrt:~# ubus call system board
{
	"kernel": "6.6.86",
	"hostname": "OpenWrt",
	"system": "ARMv8 Processor rev 3",
	"model": "Raspberry Pi 4 Model B Rev 1.5",
	"board_name": "raspberrypi,4-model-b",
	"rootfs_type": "ext4",
	"release": {
		"distribution": "OpenWrt",
		"version": "24.10.1",
		"revision": "r28597-0425664679",
		"target": "bcm27xx/bcm2711",
		"description": "OpenWrt 24.10.1 r28597-0425664679",
		"builddate": "1744562312"
	}
}
root@OpenWrt:~# 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 'fdfa:98cd:e91::/48'

config device
	option name 'br-lan'
	option type 'bridge'
	list ports 'eth0'

config interface 'lan'
	option device 'br-lan'
	option proto 'static'
	option ipaddr '192.168.1.21'
	option netmask '255.255.255.0'
	option ip6assign '60'

root@OpenWrt:~# cat /etc/config/wireless

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/soc/fe300000.mmcnr/mmc_host/mmc1/mmc1:0001/mmc1:0001:1'
	option band '5g'
	option channel '36'
	option htmode 'VHT80'
	option disabled '1'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'OpenWrt'
	option encryption 'none'

root@OpenWrt:~# 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'
	option dhcpv6 'server'
	option ra 'server'
	list ra_flags 'managed-config'
	list ra_flags 'other-config'

config dhcp 'wan'
	option interface 'wan'
	option ignore '1'

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

root@OpenWrt:~# cat /etc/config/firewall
config defaults
	option syn_flood	1
	option input		REJECT
	option output		ACCEPT
	option forward		REJECT
# Uncomment this line to disable ipv6 rules
#	option disable_ipv6	1

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

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

config forwarding
	option src		lan
	option dest		wan

# We need to accept udp packets on port 68,
# see https://dev.openwrt.org/ticket/4108
config rule
	option name		Allow-DHCP-Renew
	option src		wan
	option proto		udp
	option dest_port	68
	option target		ACCEPT
	option family		ipv4

# Allow IPv4 ping
config rule
	option name		Allow-Ping
	option src		wan
	option proto		icmp
	option icmp_type	echo-request
	option family		ipv4
	option target		ACCEPT

config rule
	option name		Allow-IGMP
	option src		wan
	option proto		igmp
	option family		ipv4
	option target		ACCEPT

# Allow DHCPv6 replies
# see https://github.com/openwrt/openwrt/issues/5066
config rule
	option name		Allow-DHCPv6
	option src		wan
	option proto		udp
	option dest_port	546
	option family		ipv6
	option target		ACCEPT

config rule
	option name		Allow-MLD
	option src		wan
	option proto		icmp
	option src_ip		fe80::/10
	list icmp_type		'130/0'
	list icmp_type		'131/0'
	list icmp_type		'132/0'
	list icmp_type		'143/0'
	option family		ipv6
	option target		ACCEPT

# Allow essential incoming IPv6 ICMP traffic
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

# Allow essential forwarded IPv6 ICMP traffic
config rule
	option name		Allow-ICMPv6-Forward
	option src		wan
	option dest		*
	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
	option limit		1000/sec
	option family		ipv6
	option target		ACCEPT

config rule
	option name		Allow-IPSec-ESP
	option src		wan
	option dest		lan
	option proto		esp
	option target		ACCEPT

config rule
	option name		Allow-ISAKMP
	option src		wan
	option dest		lan
	option dest_port	500
	option proto		udp
	option target		ACCEPT


### EXAMPLE CONFIG SECTIONS
# do not allow a specific ip to access wan
#config rule
#	option src		lan
#	option src_ip	192.168.45.2
#	option dest		wan
#	option proto	tcp
#	option target	REJECT

# block a specific mac on wan
#config rule
#	option dest		wan
#	option src_mac	00:11:22:33:44:66
#	option target	REJECT

# block incoming ICMP traffic on a zone
#config rule
#	option src		lan
#	option proto	ICMP
#	option target	DROP

# port redirect port coming in on wan to lan
#config redirect
#	option src			wan
#	option src_dport	80
#	option dest			lan
#	option dest_ip		192.168.16.235
#	option dest_port	80
#	option proto		tcp

# port redirect of remapped ssh port (22001) on wan
#config redirect
#	option src		wan
#	option src_dport	22001
#	option dest		lan
#	option dest_port	22
#	option proto		tcp

### FULL CONFIG SECTIONS
#config rule
#	option src		lan
#	option src_ip	192.168.45.2
#	option src_mac	00:11:22:33:44:55
#	option src_port	80
#	option dest		wan
#	option dest_ip	194.25.2.129
#	option dest_port	120
#	option proto	tcp
#	option target	REJECT

#config redirect
#	option src		lan
#	option src_ip	192.168.45.2
#	option src_mac	00:11:22:33:44:55
#	option src_port		1024
#	option src_dport	80
#	option dest_ip	194.25.2.129
#	option dest_port	120
#	option proto	tcp
root@OpenWrt:~#

MicroMan · May 30, 2025, 5:42pm

This is really unfortunate if it's true. I might be remembering it wrong, but I do recall that at some point I managed to get both "antennas" (2.4 GHz and 5 GHz) working.

LilRedDog · May 30, 2025, 5:55pm

That is a clean install or you have configured it too?

MicroMan · May 30, 2025, 5:58pm

I’ve done two things after the installation:
1. Changed the default password
2.Changed the device’s IP address

brada4 · May 30, 2025, 6:25pm

Press "edit" button in wireless overview, there you can select 2ghz band too. Country code required for ch 12-13. Depends on usage scenario, if you have 2.4ghz devices only then go for it, the wifi onboard suppors (4 APs) or (one STA/scan + one AP), so for moment of scan all but one APs will disappear.

LilRedDog · May 30, 2025, 6:30pm

Your install is corrupted if you have only done 2 things.
Put Pi OS on the card and install it.
Do the updates.

This does two things:
It completely clears the card, which is sometimes a problem and settings are not overwritten.
The updates will ensure the pi4 has the latest bootloader.

Then flash the card to OpenWrt and let's see the cat calls again.

MicroMan · May 30, 2025, 6:46pm

A bit embarrassing perhaps, but yes — the 2.4 GHz option was indeed there in the settings, just like you said.

Of course, since the device only has a single antenna, it can’t use both 2.4 GHz and 5 GHz frequencies at the same time.

Thanks to everyone who helped — this clarified things and I got my device working

LilRedDog · May 31, 2025, 12:15am

I'm glad you got it working.

It still has/shows configurations you say you did not make.

IOW:
Those are not default values; but it works.
¯_(ツ)_/¯

MicroMan · May 31, 2025, 8:39am

That's true. This does feel a bit strange, since my memory is different from the last time I used OpenWRT on a Raspberry Pi 4. I’m planning to try the Pi OS overwrite method you mentioned, and then flash OpenWRT again after that.

Right now, I’ve flashed OpenWRT to the card using GNOME Disks on Linux Mint:
-Frist formatted the card and then flashed the OpenWRT image.

MicroMan · May 31, 2025, 10:50am

I just did the flashing based on your instructions. I used the Pi Imager to write Pi OS to the card first, and then used the same tool to flash OpenWRT.
And still, I’m seeing the same "issue" as before.

root@OpenWrt:~# ubus call system board
{
	"kernel": "6.6.86",
	"hostname": "OpenWrt",
	"system": "ARMv8 Processor rev 3",
	"model": "Raspberry Pi 4 Model B Rev 1.5",
	"board_name": "raspberrypi,4-model-b",
	"rootfs_type": "ext4",
	"release": {
		"distribution": "OpenWrt",
		"version": "24.10.1",
		"revision": "r28597-0425664679",
		"target": "bcm27xx/bcm2711",
		"description": "OpenWrt 24.10.1 r28597-0425664679",
		"builddate": "1744562312"
	}
}
root@OpenWrt:~# 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 'fd2f:50f8:114b::/48'

config device
	option name 'br-lan'
	option type 'bridge'
	list ports 'eth0'

config interface 'lan'
	option device 'br-lan'
	option proto 'static'
	option ipaddr '192.168.1.1'
	option netmask '255.255.255.0'
	option ip6assign '60'

root@OpenWrt:~# cat /etc/config/wireless

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/soc/fe300000.mmcnr/mmc_host/mmc1/mmc1:0001/mmc1:0001:1'
	option band '5g'
	option channel '36'
	option htmode 'VHT80'
	option disabled '1'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'OpenWrt'
	option encryption 'none'

root@OpenWrt:~# 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'
	option dhcpv6 'server'
	option ra 'server'
	option ra_slaac '1'
	list ra_flags 'managed-config'
	list ra_flags 'other-config'

config dhcp 'wan'
	option interface 'wan'
	option ignore '1'

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

root@OpenWrt:~# cat /etc/config/firewall
config defaults
	option syn_flood	1
	option input		REJECT
	option output		ACCEPT
	option forward		REJECT
# Uncomment this line to disable ipv6 rules
#	option disable_ipv6	1

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

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

config forwarding
	option src		lan
	option dest		wan

# We need to accept udp packets on port 68,
# see https://dev.openwrt.org/ticket/4108
config rule
	option name		Allow-DHCP-Renew
	option src		wan
	option proto		udp
	option dest_port	68
	option target		ACCEPT
	option family		ipv4

# Allow IPv4 ping
config rule
	option name		Allow-Ping
	option src		wan
	option proto		icmp
	option icmp_type	echo-request
	option family		ipv4
	option target		ACCEPT

config rule
	option name		Allow-IGMP
	option src		wan
	option proto		igmp
	option family		ipv4
	option target		ACCEPT

# Allow DHCPv6 replies
# see https://github.com/openwrt/openwrt/issues/5066
config rule
	option name		Allow-DHCPv6
	option src		wan
	option proto		udp
	option dest_port	546
	option family		ipv6
	option target		ACCEPT

config rule
	option name		Allow-MLD
	option src		wan
	option proto		icmp
	option src_ip		fe80::/10
	list icmp_type		'130/0'
	list icmp_type		'131/0'
	list icmp_type		'132/0'
	list icmp_type		'143/0'
	option family		ipv6
	option target		ACCEPT

# Allow essential incoming IPv6 ICMP traffic
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

# Allow essential forwarded IPv6 ICMP traffic
config rule
	option name		Allow-ICMPv6-Forward
	option src		wan
	option dest		*
	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
	option limit		1000/sec
	option family		ipv6
	option target		ACCEPT

config rule
	option name		Allow-IPSec-ESP
	option src		wan
	option dest		lan
	option proto		esp
	option target		ACCEPT

config rule
	option name		Allow-ISAKMP
	option src		wan
	option dest		lan
	option dest_port	500
	option proto		udp
	option target		ACCEPT


### EXAMPLE CONFIG SECTIONS
# do not allow a specific ip to access wan
#config rule
#	option src		lan
#	option src_ip	192.168.45.2
#	option dest		wan
#	option proto	tcp
#	option target	REJECT

# block a specific mac on wan
#config rule
#	option dest		wan
#	option src_mac	00:11:22:33:44:66
#	option target	REJECT

# block incoming ICMP traffic on a zone
#config rule
#	option src		lan
#	option proto	ICMP
#	option target	DROP

# port redirect port coming in on wan to lan
#config redirect
#	option src			wan
#	option src_dport	80
#	option dest			lan
#	option dest_ip		192.168.16.235
#	option dest_port	80
#	option proto		tcp

# port redirect of remapped ssh port (22001) on wan
#config redirect
#	option src		wan
#	option src_dport	22001
#	option dest		lan
#	option dest_port	22
#	option proto		tcp

### FULL CONFIG SECTIONS
#config rule
#	option src		lan
#	option src_ip	192.168.45.2
#	option src_mac	00:11:22:33:44:55
#	option src_port	80
#	option dest		wan
#	option dest_ip	194.25.2.129
#	option dest_port	120
#	option proto	tcp
#	option target	REJECT

#config redirect
#	option src		lan
#	option src_ip	192.168.45.2
#	option src_mac	00:11:22:33:44:55
#	option src_port		1024
#	option src_dport	80
#	option dest_ip	194.25.2.129
#	option dest_port	120
#	option proto	tcp

brada4 · May 31, 2025, 11:10am

Kind of enable button looks inviting.

LilRedDog · May 31, 2025, 5:35pm

When you installed Pi OS did you expand the file system to use the entire card?

You can try

firstboot -y && reboot

in terminal or SSH. It won't hurt.

psherman · May 31, 2025, 6:11pm

Expanding the filesystem won't have any impact here. Although may be useful to the OP, it is a bit tangential / off-topic.

But sticking with the issue at hand about the radio in the Pi...

The Pi has only a single radio.
It does not support simultaneous dual band operation.
But it can be changed between 2.4 and 5G operation.

The /etc/config/wireless file will look like this (default or near-default state; note: I have not set the country code here, but it should be done if you're using wifi, and obviously the radio is disabled here):

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/soc/fe300000.mmcnr/mmc_host/mmc1/mmc1:0001/mmc1:0001:1'
	option channel '36'
	option band '5g'
	option htmode 'VHT80'
	option disabled '1'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network ''
	option mode 'ap'
	option ssid 'OpenWrt'
	option encryption 'none'

By changing the first stanza's band to 2g, you can use the radio in that mode (don't forget to also change the channel and ht mode, etc.):

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/soc/fe300000.mmcnr/mmc_host/mmc1/mmc1:0001/mmc1:0001:1'
	option channel 'auto'
	option band '2g'
	option htmode 'HT20'
	option disabled '1'
	option cell_density '0'

The change can also be affected by using LuCI: Network > Wireless > [Edit] the SSID with mode Master > Operating Frequency where AC = 5GHz, and N = 2.4GHz. If you use LuCI, it will also update the other parameters for you automatically as shown in the snippets above.

LilRedDog · May 31, 2025, 9:29pm

psherman:

config wifi-device 'radio0'
	option type 'mac80211'
	option path 'platform/soc/fe300000.mmcnr/mmc_host/mmc1/mmc1:0001/mmc1:0001:1'
	option channel 'auto'
	option band '2g'
	option htmode 'HT20'
	option disabled '1'   <---- ?
	option cell_density '0'

Needs to be 0.

psherman · May 31, 2025, 9:31pm

Right. I pointed out that what I shared had the radio disabled.

LilRedDog · May 31, 2025, 9:35pm

Not sure that is obvious to OP.

Regardless:
They have gotten the radio working.
Are you going to clean up the rest of the configs?

MicroMan · June 1, 2025, 3:40pm

hanks a lot for the reply. I've now got a clear and well-explained answer to my question.

This Raspberry Pi will only be used as a test server with a small Wi-Fi AP so I can connect to it and play around a bit

I really should’ve realized from the start that such a small box can only have one antenna, which means only one frequency band can be used at a time. Lesson learned!