Wifi 5G dead after few hour (MT7612EN)

Hi. When I use lede 17.01 with full wpad (+ hostapd-utils) the 5G wifi auto disable after a few hour and can't be enabled again (syslog didn't show anything suspicious). Revert back to 17.01-rc1 have no problem. Maybe the problem come from 802.11w support ? My device is Archer C50