Chosen Solution
I have tried a reset and done everything WiFi works over Bluetooth using my iPhone but is very slow, It used to work just fine but now it doesnt it is a 16GB iPad Air 2.
This will not be an antenna issue. If the Wi-Fi is greyed out you defiantly have a board issue. You will need to check that the Wi-Fi chip is getting power, if it is you will need to re-ball or replace the chip. If it isn’t getting power you will need to find the faulty component that has failed. Microsoldering will be needed to fix this problem.
It sounds like it could be an issue with the Wi-Fi Antenna. If you follow this guide to check the state of the antenna. I would attempt to reseat the antenna before attempting a replacement. Otherwise, it sounds like it could be an issue with the logic board.
