40 MHz not working on TL-WR1043ND/N

Hi, I have some issues with my router and AP. when I want to switch to 40 MHz it doesn't work, it keep on 20MHz.
My router: TL-WR1043ND (v2)
Dump AP: TL-WR1043N (v5) they both have the same problem.

Firmware: OpenWrt 18.06.0-rc2 (on 17.04 same problem)

config wifi-device 'radio0'
option type 'mac80211'
option hwmode '11g'
option path 'platform/qca955x_wmac'
option htmode 'HT40'
option legacy_rates '1'
option channel '1'
option country 'NL'
option txpower '20'

uci set wireless.radio0.noscan=1