I have an iPhone 4 that won't connect to wifi, either to mobile wifi or home wifi. It is greyed out in settings and won't switch on anymore. I have done network settings reset, all settings reset, restored the phone but to no avail. From what I can see I'm not alone and it is a software error on the part of Apple or even a hardware fault. It looks like it will have to be returned to Vodafone for repair.