I think it is a VPN issue. I have AT&T for a cell provider, and I have their Call Protect and Mobile Security apps installed. Mobile Security has a VPN feature that my phone flashed at the top right that it was enabled. Go into iPhone settings and turn off VPN, and everything works fine. Turn VPN back on and things go to crap.
edit: I just deleted the AT&T Mobile Security app off my phone. It says it only enables VPN when you connect to an unsecure WiFi router. I've noticed that the app says I'm connected to a secure WiFi router(mine), but it still always enables the VPN. I never connect to unsecure routers, and I don't really see a benefit to anything with the app. So, just got rid of it.