WRT3200ACM wifi unstable

I have install LEDE 18.06.01 ( OpenWrt 18.06.1 r7258-5eb055306f ) on linksys WRT3200ACM works fine
configure my lan with luci but the wifi 2.4 GHZ drop some paquet randomly
here an exemple with 250 ping to another client on lan :https://pastebin.com/xakAbxV8
My network configuration : https://pastebin.com/t20tA8N3

Any idea who is the problem ?

Maybe try this: Davidc502- wrt1200ac wrt1900acx wrt3200acm wrt32x builds ?