[MT7621][Xiaomi Redmi AC2100] 160Mhz for 5GHz WiFi, low performance

Hello everyone!
I have mesh WiFi network set up with 802.11s (without mesh11sd). Mesh consist of three Xiaomi Redmi AC2100 routers. First one is connected to ISP and other ones are just kind of "dumb AP' which work as relay using 802.11s mesh. OpenWRT version is 23.05.5.

Everything works great but what I am trying to achieve is to increase speed of communication between mesh nodes. How I measure this speed: I've installed iperf3 on all router and start it as server on "main" (which is connected to ISP) router and as client on all other router. Such measurement shows me approx. 200 Mb\s.

If I understand correctly meaning of "wifi channel width", I expected increase of speed when switching from 80 MHz width to 160 MHz, but actually I got significant decrease to approx. 40 Mb\s.

Why it works in this way? Did I miss something in configuration?

Here are my configs:

Wireless config of main router
config wifi-device 'radio0'
	option type 'mac80211'
	option path '1e140000.pcie/pci0000:00/0000:00:01.0/0000:02:00.0'
	option band '2g'
	option cell_density '0'
	option htmode 'HT40'
	option channel '4'
	option country 'RU'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option encryption 'psk2'
	option ssid 'zu'
	option key '...'
	option ieee80211r '1'
	option mobility_domain '123F'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'

config wifi-device 'radio1'
	option type 'mac80211'
	option path '1e140000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0'
	option band '5g'
	option cell_density '0'
	option htmode 'VHT80'
	option country 'RU'
	option channel '36'

config wifi-iface 'default_radio1'
	option device 'radio1'
	option network 'lan'
	option mode 'ap'
	option encryption 'psk2'
	option ssid 'zu'
	option key '...'
	option ieee80211r '1'
	option mobility_domain '123F'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'

config wifi-iface 'wifinet2'
	option device 'radio0'
	option mode 'ap'
	option ssid 'zu-iot'
	option encryption 'psk2'
	option key '...'
	option network 'iot'
	option ieee80211r '1'
	option mobility_domain '4F59'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'

config wifi-iface 'wifinet3'
	option ifname 'zu_mesh'
	option device 'radio1'
	option mode 'mesh'
	option encryption 'sae'
	option mesh_id 'zu-mesh'
	option mesh_fwding '1'
	option mesh_rssi_threshold '0'
	option key '...'
	option network 'lan'

config wifi-iface 'wifinet4'
	option ifname 'zu_iot_mesh'
	option device 'radio1'
	option mode 'mesh'
	option encryption 'sae'
	option mesh_id 'zu-iot-mesh'
	option mesh_fwding '1'
	option mesh_rssi_threshold '0'
	option key '...'
	option network 'iot'

config wifi-iface 'wifinet5'
	option device 'radio1'
	option mode 'ap'
	option ssid 'zu-iot'
	option encryption 'psk2'
	option key '...'
	option ieee80211r '1'
	option mobility_domain '4F59'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'
	option network 'iot'
Wireless config of dump router
config wifi-device 'radio0'
	option type 'mac80211'
	option path '1e140000.pcie/pci0000:00/0000:00:01.0/0000:02:00.0'
	option channel '4'
	option band '2g'
	option htmode 'HT40'
	option cell_density '0'
	option country 'RU'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'zu'
	option encryption 'psk2'
	option key '...'
	option ieee80211r '1'
	option mobility_domain '123F'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'
	option reassociation_deadline '20000'

config wifi-device 'radio1'
	option type 'mac80211'
	option path '1e140000.pcie/pci0000:00/0000:00:00.0/0000:01:00.0'
	option channel '36'
	option band '5g'
	option htmode 'VHT80'
	option cell_density '0'
	option country 'RU'

config wifi-iface 'default_radio1'
	option device 'radio1'
	option network 'lan'
	option mode 'ap'
	option ssid 'zu'
	option encryption 'psk2'
	option key '...'
	option ieee80211r '1'
	option mobility_domain '123F'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'
	option reassociation_deadline '20000'

config wifi-iface 'wifinet3'
	option ifname 'zu_mesh'
	option device 'radio1'
	option mode 'mesh'
	option encryption 'sae'
	option mesh_id 'zu-mesh'
	option mesh_fwding '0'
	option mesh_rssi_threshold '0'
	option key '...'
	option network 'lan'

config wifi-iface 'wifinet5'
	option device 'radio0'
	option mode 'ap'
	option ssid 'zu-iot'
	option encryption 'psk2'
	option key '...'
	option network 'iot'
	option ieee80211r '1'
	option mobility_domain '4F59'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'
	option reassociation_deadline '20000'

config wifi-iface 'wifinet6'
	option ifname 'zu_iot_mesh'
	option device 'radio1'
	option mode 'mesh'
	option encryption 'sae'
	option mesh_id 'zu-iot-mesh'
	option mesh_fwding '0'
	option mesh_rssi_threshold '0'
	option key '...'
	option network 'iot'

config wifi-iface 'wifinet7'
	option device 'radio1'
	option mode 'ap'
	option ssid 'zu-iot'
	option encryption 'psk2'
	option key '...'
	option ieee80211r '1'
	option mobility_domain '4F59'
	option ft_over_ds '0'
	option ft_psk_generate_local '1'
	option network 'iot'
	option reassociation_deadline '20000'

The 80Mhz and 160Mhz is the Radio Spectrum Used
not the amount of data per second
the best way to make them faster is connect them via cable
as real Dump AP not a Mesh radio uplink