When I leave a Wi-Fi area, my iPhone properly switches to 4G or LTE... however many times - even when I have good signal strength - I am not able to connect to the internet on the cellular connection after it switches from Wi-Fi. If I try to load a webpage, it just stalls out. The only way I am able to get the connection working again is by turning on/off Airplane Mode or restarting the phone. Seems to only be an issue when going from Wi-Fi to cellular. I am on AT&T. Has anyone else experienced this?