So after looking around the web i think this problem occurs when the phone's tendency to overheat messes up somthing in th wifi ic chip. Now i don't know the full break down of the phone's hardware but I have seen some fixes which involve putting a small bit of thermal pad on the wifi ic chip. I havent tried it yet on my broken phone but im pretty confident it'll fix the problem.
Tldr: Thermal pad placed on you wifi ic chip could help.