Hi All!
This heat treatment trick worked for me too! I had the same issue with my 4S. Resetting the network setting didn't work. Neither did the freezer help. Then I went on with the heating trick.
Actually, I tried an easier version, found on YouTube:
- I left my iPhone switched on.
- Took my hair dryer on maximum heat settings and started to heat the phone around the earpiece / front cam area on the top.
- I did this for a few minutes until my phone displayed it is overheated and needs to cool down before use.
- Turned it off and waited for it to cool down.
- Then I turned it on and wifi was back!
Awesome!