Force mode 802.11 for station using wpa_supplicant

[Vu Hai NGUYEN]

>Hi all,
>I wonder if we can use wpa_supplicant to force mode 802.11 for a station when it connects to an AP.
>For example my AP using hostapd and was set up in 802.11ac VHT80, channel 36.
>Normally all the device support 802.11n can connect to that AP too.
>But because the wifi module in my station is the same as my AP and they are all support 802.11ac so
>if I set up the channel 36 for my station it connect automatically with my AP in mode 802.11ac VHT80.
>Is there any way that I can force my station to connect to my AP in mode 802.11n HT20 or HT40?
>I don't see any parameter in the configuration file of wpa_supplicant that allow me to do this.

If I set the parameter "disable_vht=1" in the configuration file of wpa_supplicant, my station can connect in 
mode 802.11nHT40  with my AP (set up in 802.11ac VHT80). 
Then I add "disable_ht40=1", but my Station still connects to my AP in mode 802.11n HT40 (I verify this
by checking bandwidth and rate report from command "iw").
I added "disabled_ht20" but this did not create any effect too. Any one gets the same issue like me?
Here is an example of my configuration file for wpa_supp:

ctrl_interface=/var/run/wpa_supplicant
eapol_version=1
ap_scan=1
fast_reauth=0
network={
	ssid="ath10k"
	disable_ht=1
	disable_vht=1
	scan_freq=5220
	pairwise=CCMP
	group=TKIP CCMP
	auth_alg=OPEN
	psk="password"
}

Thanks,
NGUYEN Vu Hai
Acita-Sodielec
Route de Mayres - B.P. 9
12100 St GEORGES DE LUZENCON
FRANCE