@bruce good news. I think i have fix it. with version 24. Is not that stable... sometimes is 900mbps sometimes 600mbps but better then before.
uci set wireless.radio1.country='CN'
uci set wireless.radio1.txpower='30'
uci commit
uci commit wireless
reload_config
also i think the irqbalance is not working because when i do speedtests the CPU is not getting load at all.
Thanks again for all your help Bruce