Iphone 6, 6plus no wifi

Iphone 6 plus no wifi, ihave ip6 with same issue. Wifi ic is 100% work, changed to new one but problem still the same. When i put old wifi ic to another phone it works fine. Voltage is ok, wifi ic is ok, every jumper and resistor is checked and ok. What is going on with this wifi in this phones???
I don’t know where to look issue. Some ideas?