I have had some issues with wifi & personal hotspot on my iphone and iPad so I had to reset my network setting. The symptoms are obvious going to a website and the page is not loading or making your iphone a hotspot (Tethering) and you are getting no connectivity between your iphone and tethered device iPad/Notebook.
Reset network settings
To reset your network settings, tap Settings > General, then tap Reset > Reset Network Settings.
When the device restarts, try to locate and join the Wi-Fi network again.