I’m having trouble connecting to the internet

You might need to update your carrier settings.

Update your carrier settings on your iPhone or iPad

https://support.apple.com/en-us/HT201270

RobWilson13 Said:

"I am having trouble connecting to the Internet I’m getting an error signal on Cellular connection"

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Troubleshooting iPhone WiFi:

Four Thoughts:

A. Clear Temporary Internet Files:

If connecting is unsuccessful, try clearing out your Temporary Internet Files: History, Cache, and Cookies

Go Here: Clear your Safari Browser History and Set Up Content Blockers on your iPhone, iPad, or iPod touch- Apple Support

B. Try manually restarting your iPhone:

1. Go To: Settings
2. Select: General
3. Scroll to: the Very Bottom
4. Select: Shut Down
5. Slide Finger: to the Right
6. Wait: 30 Seconds
7. Power One: the iPhone
8. Try this Once More

C. Is Cellular Data ALWAYS Enabled?:

Cellular Data always overrules Wi-Fi. So, if applicable, disable Cellular Data, if enabled, and see if you get Wi-Fi to work.

D. Troubleshooting Connectivity:

Wi-Fi: If your iPhone won’t Connect to a Wi-Fi Network - Apple Support