5G is not working in my iPhone 16 Pro Max with iOS 18.3

Subject: iPhone 16 Pro Max (Model A3297) - No 5G Connection Despite Compatible SIM and Region

Hello,

I recently purchased an iPhone 16 Pro Max (Model A3297, iOS 18.3), and I’m experiencing an issue where the device never connects to 5G — only LTE is available — despite the following conditions:

- I am using fully compatible 5G SIM cards (Irancell and MCI), which worked flawlessly on my previous iPhone (15 Pro) in the exact same location.

- The iPhone region is set to United States.

- 5G is enabled in Settings (both “5G Auto” and “5G On” tested).

- I performed a full Reset Network Settings.

- Carrier Settings show no update available.

- Both SIMs support 5G and are provisioned correctly by the carriers.

- My area has active 5G coverage and worked on my previous device.

Still, the phone only connects to LTE and never to 5G. I suspect this may be an issue with iOS 18.3 or an incomplete carrier configuration for the A3297 model in my region.

Could you please advise whether this is a known issue and if it will be addressed in a future iOS update? Is there any manual provisioning or carrier profile that can be installed to resolve this?

Thank you in advance for your support.

[Re-Titled by Moderator]