Why won’t my iPhone connect to 4G?

In the case of 4G not working on iPhone, it could be an issue with the service provider – probably the cellular networks bands aren’t compatible with your iPhone, just in case the operators in your region aren’t following standards which is very rare. Otherwise, it’s probably a glitch on your iPhone and few trial and error methods could get the iPhone get connected to 4G network again.

1. Check Cellular Connection

2. Turn Airplane Mode On & Off

3. Remove the SIM Card and Reboot your iPhone

4. Is the SIM PIN Turned On? – Switch it Off

5. Reset Network Settings

At least one of the methods described above should solve the problem. If not, you should pay a visit to the nearest authorized Apple service center.

I know this is quite old, but if anyone lands here, I had the same problem, my iPhone suddenly had issues transitioning between 4g and WiFi. So if I left my WiFi and came back into it, it would take about 2-3 hours before it would connect again.

I did absolutely everything people recommend: turned it off and on, backed it up and restored the whole thing back to factory settings, changed every possible setting. Nothing worked, then I popped out the sim and my phone instantly connected to WiFi. I ordered a new sim and it works fine now.

Yes, I had the same problem with Optus in Australia. I use it for mobile data and a printer with an old Wifi system. Using 4G means it had to switch from my old Wifi with the printer on it and for some reason it’s default. So I just have to switch my Wifi off in the phone, and that was the only my problem I saw with the smart phone not adapting with the user.