DAWN 802.11k slow to return to 5Ghz

Installing and Using OpenWrt
1

Hello

I try to install DAWN for band steering between 5Ghz and 2.4Ghz

The transition between 5Ghz to 2.4 with iPhone XR is fast

But, when I come back in the AP room, the iPhone take a lot before return to 5Ghz, how I can improve it ? I measured, I'm in a good zone for 5ghz when I reach -40 on RSSI of my 2.4 Ghz

There is my config file :

config local
	option loglevel '0'

config network
	option broadcast_ip '192.168.10.255'
	option server_ip '192.168.10.2'
	option broadcast_port '1025'
	option tcp_port '1026'
	option network_option '2'
	option shared_key 'Niiiiiiiiiiiiick'
	option iv 'Niiiiiiiiiiiiick'
	option use_symm_enc '0'
	option collision_domain '-1'
	option bandwidth '-1'

config hostapd
	option hostapd_dir '/var/run/hostapd'

config times
	option con_timeout '60'
	option update_client '10'
	option remove_client '15'
	option remove_probe '30'
	option remove_ap '460'
	option update_hostapd '10'
	option update_tcp_con '10'
	option update_chan_util '5'
	option update_beacon_reports '20'

config metric 'global'
	option min_probe_count '3'
	option bandwidth_threshold '6'
	option use_station_count '0'
	option max_station_diff '1'
	option eval_probe_req '0'
	option eval_auth_req '0'
	option eval_assoc_req '0'
	option kicking '3'
	option kicking_threshold '20'
	option deny_auth_reason '1'
	option deny_assoc_reason '17'
	option min_number_to_kick '3'
	option chan_util_avg_period '3'
	option set_hostapd_nr '1'
	option duration '0'
	option rrm_mode 'pat'

config metric '802_11g'
	option initial_score '80'
	option ht_support '5'
	option vht_support '5'
	option no_ht_support '0'
	option no_vht_support '0'
	option rssi '15'
	option rssi_val '-60'
	option low_rssi_val '-80'
	option low_rssi '-15'
	option chan_util '0'
	option chan_util_val '140'
	option max_chan_util '-15'
	option max_chan_util_val '170'
	option rssi_weight '0'
	option rssi_center '-70'

config metric '802_11a'
	option initial_score '100'
	option ht_support '5'
	option vht_support '5'
	option no_ht_support '0'
	option no_vht_support '0'
	option rssi '15'
	option rssi_val '-60'
	option low_rssi_val '-70'
	option low_rssi '-15'
	option chan_util '0'
	option chan_util_val '140'
	option max_chan_util '-15'
	option max_chan_util_val '170'
	option rssi_weight '0'
	option rssi_center '-65'

Thanks you