I've been using note 3 for 4 years and currently it has phronesis rom 7.0.
Last week, after i charged with my powerbank, suddenly wifi stopped working, stucked at 'enabling wifi'. I rebooted a few million times, cleaned unnecessary apps including the last ones, hard reset, reinstalled rom, shook it, dropped it to the floor, threw it to the wall, but didnt help at all. And i thought it's got broken as it's already 4 year old phone.
A few days later, when my charge was at 3%, the back of of the phone, right next to the camera heated too much, despite i was doing nothing, i got panicked and removed the battery.
10 min later, placed it again, booted the phone, and tadaaa, wifi was working, the back side was keeping its cool, phone was smoother and charge level was %35 or so.
Then i thought, wifi issue was not a hardware thing but instead it was related to wrong battery stats. When the charge level was again 2% i removed the battery again, waited for a few min and placed again. It was again %25 percent,( didnt last long though,) but wifi again was not working.
Moving from that point, i fully charged the phone, calibrated battery, removed, replaced etc... but didnt work.
I deleted the file data/misc/wifi, it didnt work.
Afaik, blutooth and wifi use a common chip and if wifi is failing cos of a hardware issue, bluetooth is not supposed to work as well. Yet, my bluetooth works fine. It's just wifi.
I dont know how to fix it.