WIFI 2.4GHz not working, but 5GHz works

Hello,

I have set up a WIFI where I can connect to 5GHz, but older devices can not connect to 2.4GHz WIFI. Other questions/answers from here did not help me yet.

I can share all the parameters I have below or if anything additional is needed of course also.

Thank you very much for any help

Best regards

Model accoding to LuCI: D-Link DIR-2660 A1
Architecture: MediaTek MT7621 ver:1 eco:3
Firmware Version: OpenWrt 21.02.0 r16279-5cc0535800 / LuCI openwrt-21.02 branch git-21.231.26241.422c175
Kernel Version: 5.4.143


cat /etc/config/wireless

config wifi-device 'radio0'
	option type 'mac80211'
	option channel '11'
	option hwmode '11g'
	option path '1e140000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0'
	option cell_density '0'
	option country 'AT'
	option htmode 'HT20'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option mode 'ap'
	option ssid '...'
	option network 'lan'
	option encryption 'sae-mixed'
	option ieee80211w '1'
	option key 'pass'
	option wds '1'
	option wmm '0'

config wifi-device 'radio1'
	option type 'mac80211'
	option channel '36'
	option hwmode '11a'
	option path '1e140000.pcie/pci0000:00/0000:00:01.0/0000:02:00.0'
	option cell_density '0'
	option htmode 'VHT80'
	option country 'AT'

config wifi-iface 'default_radio1'
	option device 'radio1'
	option mode 'ap'
	option ssid '...'
	option ieee80211w '2'
	option encryption 'sae-mixed'
	option network 'lan'
	option key 'pass'

Likely the reason.

First try with the bare minimum configuration. If needed, delete what you have already configured and try without any encryption or special setting. Move your way up adding one setting at a time, then test that the clients can still connect.

The devices which connect to 5GHz can also connect to 2,4GHz?

Thanks for your reply.

I think that both networks are conflicting each other. When I disable the 5GHz WIFI, then it works and all devices connect to the 2,4GHz WIFI.

This is maybe a complete beginner question, but I need to ask:
Is it a problem, if the 2,4GHz WIFI and 5GHz WIFI have the same SSID? To my mind, I thought that the devices are smart enough to choose their frequency.

Thank you

It is not a problem. Dual band devices will decide which one is better to connect to.