Dear Iqoo,
Please check video for your refrence, wifi is working in funtouch 13 software which is downgraded by service center for wifi problem, it clearly shows that wifi problem caused by your updated software funtouch 14. please change mother board of handset or send proper software update to solve issue. with same motherboard wifi is working in funtouch 13 software and with same mother board wifi is not working with update version of your software funtouch 14. so Iqoo is sending updates to phone to create problem and make money by giving paid service as after warranty problem is caused.