My Asus g551jm have first n 7260 and now ac7260. The have the same problem. Wifi is very very slowwwwww, on other divices its everything ok but on n7260 and ac7260 my internet speed slows from 30Mb to 5Mb..... WHY ??

y Asus g551jm have first n 7260 and now ac7260. The have the same problem. Wifi is very very slowwwwww, on other divices its everything ok but on n7260 and ac7260 my internet speed slows from 30Mb to 5Mb..... WHY ??