my iphone

Disable Wi-Fi Networking Services
Many users have reported that they’ve solved their issues by disabling Wi-Fi Networking under Settings > Privacy > Location Services > System Services. This only relates to your location being used for Wi-Fi Networking, so it doesn’t disable Wi-Fi entirely.

Reset Network Settings
Most networking related issues I’ve experienced have been fixed after resetting network settings. Resetting these settings flushes caches and clears DHCP settings and other networking related info. To reset network settings, open the Settings app and navigate to Settings > General > Reset and tap on Reset Network Settings.

Set Custom DNS
Often times, if your ISPs DNS servers are having problems, you can switch to Google DNS or OpenDNS. You can follow the instructions in the post linked below to change your DNS settings.


Restore and Setup as new iPhone
If none of these tips fix your issues, the last resort is to restore your iPhone or iPad via iTunes, and set it up as a new device. This way, you start afresh, and get rid of possibly problematic customisations and settings on your device. Follow the instructions in the post linked below to do a clean restore to the latest version of iOS via iTunes.