Check for a carrier settings update
Carrier settings are updated separately from iOS itself, and a major update frequently prompts a new bundle. Settings → General → About, waited on for about thirty seconds, will show a carrier update prompt if one exists. Install it and restart.
If nothing appears, toggling Airplane Mode on and off forces a fresh network registration, which is often enough on its own after an update. Do this before anything more disruptive.
Reset network settings
Settings → General → Transfer or Reset iPhone → Reset → Reset Network Settings rebuilds the cellular configuration from scratch. On a physical SIM this is non-destructive and usually resolves the problem outright.
On an eSIM the same reset is safe — the eSIM itself is not deleted — but the device will re-register with the network afterwards, which can take a few minutes. Do not delete the eSIM: on many carriers re-adding it requires contacting support.
5G and network mode problems
A phone that shows LTE where it used to show 5G is often working correctly. Beta builds change how aggressively iOS switches modes, and Settings → Cellular → Cellular Data Options → Voice & Data lets you force 5G On rather than 5G Auto to test it.
If forcing 5G produces no service at all, the interaction is with your carrier's network configuration rather than with the radio. Set it back to Auto and report it — this is a genuinely useful beta bug to file.
Rule out the beta entirely
Put your SIM or eSIM in another phone, or another SIM in yours, if you can. Carrier outages, expired plans and provisioning changes have a habit of coinciding with an update and being blamed on it.
Your carrier's status page and a quick check of whether other people on the same network nearby have service will settle it in a minute, and will save you from restoring a device over something that was never the software.
When to get off the beta
If mobile data or calls are unreliable on the phone you depend on, do not wait. Turn off Beta Updates and restore the previous release from the archived backup you made before installing — our downgrade guide covers it.
This is also the clearest argument for the point made in our main-device guide: a beta on a secondary phone is an experiment, while a beta on your only phone is a dependency.
Frequently Asked Questions
Why did I lose mobile data after installing the iOS beta?
Most often a stale carrier settings bundle or a failed network registration. Check for a carrier update in Settings → General → About, then reset network settings.
Does resetting network settings delete my eSIM?
No. The eSIM remains installed; the device simply re-registers with the network, which can take a few minutes.
Why does my iPhone show LTE instead of 5G on the beta?
Beta builds often change how iOS switches network modes. Forcing 5G On under Cellular Data Options → Voice & Data will tell you whether 5G is genuinely unavailable.
Should I delete and re-add my eSIM to fix this?
Not as a first step. Many carriers require you to contact support to reissue an eSIM, so try carrier settings, a restart and a network reset first.