s4 i9505 very slow wifi


hello its can be software problem s4 very slow wifi

i have flashed 2 firware from support 4.4.2 and 5.0.1
custumer says i update from wifi after become like that

I9505XXUFNA5_I9505OXAFNA5_I9505XXUFNA5_OXA_4.4.2.o ct