Just fyi: I didn't enable soft flow offloading. Against some dropouts on 2.4 G I've found a workaround specific to 802.1x eap-tls (radius driven corporate) wifi that works to keep our mobile phones solidly connected.
option eap_reauth_period '0'
(from my mind of another thread here : Driver cannot safely Rekeying with 801.1x - #11 by Catfriend1 )