Network connectivity issues with the latest iOS for both iPhone 17 & iPhone SE3

Few Carrier (Cellular Service Provider) does not provide Carrier Settings in full but they offer APN settings for example

• Google FI which has APN to be entered manually as h2g2
• MTN Ghana which provides APN pin to be updated manually as the internet
• BSNL in India which provides APN pin to be updated manually as bsnlnet (Watch teh GIF below)

Settings > Mobile Data > APN [under Mobile Data APN] enter the APN pin

View and edit your APN settings

If your carrier allows it, you can view your APN settings in one of the following locations: Settings > Cellular > Cellular Data Options > Cellular Network. Settings> Mobile Data > Mobile Data Options > Mobile Data Network.

View and edit your Access Point Name (APN) on your iPhone ...

Use the APN pin based on your carrier. Ask them (Your Carrrier) or search using any search engine.

If you do see the option to enter APN then the only option is given below

Carrier Update (Required): Released by your Cellular Service provider (Carrier Update), affects your Outgoing / Incoming calls, SMS, Data etc..

How to Update Carrier Settings

You can manually check for and install a carrier settings, update with these steps: Make sure your device is connected to a Wi-Fi or cellular network. Tap Settings > General > About. If an update is available, you'll see an option to update your carrier settings.

Update your carrier settings on your iPhone or iPad - Apple Support

Cellular or internet issues are not always the fault of the iOS update!  Many things can cause phone problems.  If you tell people you think it's an iOS update, it might make it harder to fix or find a solution for the real issue.

Remember, the right question often leads to the solution!

Was/Is your device Jailbroken? If that's the situation, please be informed that attributing the issues to iOS updates may not be accurate.

iOS updates aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. The majority of the issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors. This could be a pure coincidence that the iOS update affected the iPhone functions.

Before initiating a standard iOS update, it's advisable to create a backup. Have you completed this step? If yes, proceed with the restoration from the backup.

See what each update does: OS — iOS 26, About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...

It surely is not iOS 18.5 or 26.2.1 because...

I conducted a thorough search of this forum using the term 'Cellular network after iOS' and uncovered numerous posts detailing similar issues across various iOS updates. This suggests that iOS updates may not consistently be the root cause. Below are a handful of examples extracted from over 6,000 search results:

• iOS 16.4.1 installed = Cellular Network Data Issues
• IOS 17.1.2 killed my cell service!?
• why is iPhone 6s has no cellular connection after ios 15 update?
• IOS 17.1.2 Update caused major cellular network problem
• Cellular network is not recognised after updating to IOS 16.
• Re: I don't have cellular service on my iPhone after iOS 15.7.9 update
• Loss of Cell Connectivity After IOS 16.3 Update- iPhone 13 Pro Max
• Cellular error no network available after iOS update 15.4
• Cellular Issue with IOS 14
• Re: No service (cellular network) after upgrade to 14.7.1

The above issues are across many models, and iOS updates suggest the issues reported by many are device-specific and attributed to iOS updates erroneously.