Q: iphone 4s wifi greyed out.

Me too. I've restarted the settings of my iPhone. It didn't work. But when i tried the hair dryer way, it worked. But it is just for temporary, now my wifi has gone greyed out.

nope, i didn't get the solution!     

OKAY i was super scared and put the phone in the freezer the wifi worked for like 1 minute then kicks me out again.

I found a website the shows a step by step on how to fix it. I am not sure if I want to try it myself or take it to a repair shop

but the freezer definitely works as a temporary solution

https://www.ifixit.com/Guide/How+to+Fix+iPhone+4S+Wi-Fi+Grayed+Out/22167

neuralstatic..this method of yours worked for me, even after it was posted 2 years ago...thanks for sharing!

neuralstatic

my situation:

wifi would not turn on, bluetooth was fine.

reboots and reset network did not help

BUT this helped

- turning airplane mode and do not disturb on

- powering off device for 2 minutes

- powering on and disabling modes.

wifi went from "off" to "not connected" and worked fine from then on.

I too was experiencing a similar issue with my son's iPhone 4S after he used up all of his data which has never happened before. We then realised that the wifi was greyed out and the Bluetooth wouldn't work. I tried a myriad of different things I found on the web including a hard reset, resetting my network settings and finally using iTunes to restore as a new phone. None of these worked so I then tried the freezer trick which also didn't work so my final resort was to try using the heat approach. Not having a hairdryer to hand (I was at work) I did manage to locate a heat gun which I fired into the headphone socket on the top. Within a minute, I noticed on the screen that the Bluetooth was live so I turned off the heat gun and reset my network settings. Hey presto, wifi was working again. I think that due to the headphone socket being on top it easily allows rain etc to get inside especially when being held up to your ear when making calls.