Reproducible Issue with Incorrect Timezone

I’m experiencing a reproducible issue with my phone’s time zone when Date & Time setting in iOS set to automatic.

Devices & software:

iPhone 16 Pro running iOS 26.3. Issue started sometime this week and isn’t consistent.

Also observed on an iPhone 15 Pro across multiple versions of iOS 26 for 3-4 months, but currently running iOS 26.3. Did basic troubleshooting and moved device date and time to manual mode and moved on.

Issue:When the device cellular settings are set to 5G Auto with 5G Standalone enabled, the time zone switches from Mountain Time to Central Time.

Troubleshooting performed:

Rebooting devices has no impact

Recent iOS update to26.3 has no impact

Disabling 5G Standalone keeps the time zone correct.

Forcing the device to LTE only keeps the time zone correct.

Toggling Set Automatically for date & time does not resolve the issue. Including before or after reboot

Manually setting the time zone works temporarily, but switching back to automatic returns the incorrect time when 5G Standalone is active.

This behavior is consistent and repeatable.