Hello, Susan! Thank you for reaching out to us on Social Media! I regret knowing your device isn't connecting to the internet. Have you tried a Network Reset? Typically, that helps get the device back on the Network.
What if that doesn't work? I've already tried that--I have even reset the phone to factory settings and have gotten a new SIM card with no improvement. I'm using the iPhone 11 Pro Max 256G.
Allow us to take a step back. Are you stating the phone won't auto switch from Wi-Fi to cellular OR you do not have a cellular connection at all?