Fix iOS 18.4 Beta 2 No Signal After Update

Welcome to my blog! This post was originally written in Chinese and has been translated into English. If you spot any language issues or inaccuracies in the translation, feel free to point them out in the comments. Thanks for your help!

Foreword

For those using the iOS 18.4 RC version, please refer to the additional notes at the end.

System and Phone Details

• System: iOS 18.4 beta2 (iOS 18 Developer Beta)
• Phone: iPhone 14 Pro (dual SIM cards)

The Issue

After updating to iOS 18.4 beta1, I ran into a “no service” problem with my phone. I use two SIM cards: one from China Telecom and one from China Unicom. With beta1, the China Telecom card had a signal, but the China Unicom card didn’t—though this eventually got fixed (details below). After updating to beta2, the opposite happened: China Unicom had a signal, but China Telecom didn’t. The fix this time was different from beta1, so I’ll explain both solutions later in the post.

Background

Ever since the iOS 18.1 Developer Beta rolled out, people online have been reporting “no service” issues after updates. A quick look at Apple’s community forums shows that some users took their devices to Apple Support, where it was confirmed as a system glitch requiring a downgrade to resolve. This issue has stuck around through multiple updates and has gotten worse with iOS 18.4 Beta. I’ve seen plenty of chatter about it on Reddit too, but the solutions floating around online don’t fully address the root cause. So, I’m breaking it down step by step based on my own experience. One key note: if you’re stuck with no signal for a while, please head to Apple Support. It might not just be a software bug—it could be a hardware issue needing repair.

What Triggers It

In versions before iOS 18.4, forgetting to disconnect from a VPN before hitting “install now” often led to the “no service” issue post-update. But here’s the kicker: my tests with iOS 18.4 showed that even quitting the VPN beforehand didn’t prevent the problem. That’s why I wrote this guide to tackle these scenarios.

Solutions

Option 1: Wait for the Update to Finish, Then Restart

It’s a universal truth: restarting fixes a ton of tech problems, whether it’s a laptop, tablet, or phone. But why do I stress waiting until the update is fully done? Big updates like iOS 18.4 beta2 come with a lot of changes—like adding 5G Standalone (SA) support for China Telecom and China Mobile, or patching AI features—that need time to settle in. If you restart right after seeing “no service,” the system might not have finished updating, which could interrupt the process. Plus, the phone might overheat and cause more trouble.

So, wait until the update is complete (for me, that’s when the phone cools down to normal). If you still have “no service,” restart it and check again. No luck? Move on to the next step.

Option 2: Toggle Airplane Mode

On a computer, network issues often prompt people to clear the DNS, since DNS hiccups or stale caches can mess things up (though caches rarely cause big problems—still, good to cover all bases). Phones don’t have a command prompt, so we use airplane mode instead to reset the network.

Turn on airplane mode, leave the phone alone for 10 seconds, then turn it off. If the signal comes back, you’re golden—no need to keep reading. If not, next step.

Option 3: Remove and Reinsert the SIM Card

This one’s simple: pop out your SIM card, give it a quick wipe with an eraser, and put it back in. If you’re in mainland China with a physical SIM, this is a solid step 3. Using an eSIM? Skip this one.

Option 4: Reset Network Settings

Resetting network settings can sometimes bring your signal back by returning everything to default. I’ve tried this across a few updates, though, and it’s failed me lately. Still, it’s worth a shot—if your issue ties back to a settings glitch, it might work. Fair warning: I can’t promise success, and you’ll have to reconfigure permissions for every app afterward, which is a hassle.

Option 5: Update the IPCC File

Heads-up—this is just a suggestion! I saw folks on TikTok, CSDN, and Reddit claiming this fixed their issue, but it didn’t work for me. No idea why, but some people did solve it this way on iOS 18.3. If you want to try, check out this guide: Update IPCC File. (Big thanks to the person who shared it!)

Option 6: Downgrade the System

There are two flavors here, starting with a data-preserving downgrade. Pre-iOS 18.3, if an update caused this issue, downgrading was an option. When I went from iOS 18.1 to 18.2 without disabling my VPN, I got “no service” and fixed it by downgrading via Aisi Assistant. A couple of days later, I updated again (VPN off) and had no issues—probably because the VPN messed with SIM recognition the first time.

Post-iOS 18.3, though, Apple shut down this route. No downgrades or same-version reinstalls are possible now. With 18.3, you could still wipe data and downgrade, but iOS 18.4 blocks everything. Note: I’m talking Aisi Assistant here—I haven’t tested iTunes.

Option 7: Reinstall the Same Version (Flat Downgrade)

Let’s define this: reinstalling iOS 18.3 beta2 from beta3 is a “flat downgrade”—same major version, different beta. Going from 18.3.1 to 18.3 isn’t; that’s a regular downgrade. Same digits after “18” (like 18.3 to 18.3.x) mean flat; otherwise, it’s case-by-case.

Before iOS 18.3, you could do this with or without keeping data. For 18.4, third-party tools are locked out, so this door’s closed too.

Option 8: Swap SIM Cards

This is for physical SIM users only—eSIM folks can’t do it (though theoretically, maybe; use your judgment). I tried this on iOS 18.4 beta1: swapped in two different SIMs, and within seconds, the phone recognized them. Crucial tip: don’t swap back to your original SIM right away. Let it run a few minutes to fully register, then switch. My China Telecom card worked first, and China Unicom kicked in after 30 minutes. Should work for beta2 too, but I didn’t have spare SIMs to test last night.

Option 9: Last Resort—Wipe and Reinstall iOS

Every guide calls this the final fix, and someone on Apple’s forums recovered this way via Support. You’ll need to back up your data—computer backups are quick, but iCloud takes forever, so I don’t recommend it. If nothing else works, wait a day or two first. I’ve noticed one SIM often regains signal in 3–4 minutes post-update. Use that and hold off on wiping—mine fully recovered after 30 minutes last night. Rushing to reinstall could be overkill.

Final Thoughts

This post sums up every fix I’ve come across or tried myself. I’m not diving into detailed how-tos here (maybe later if there’s demand), but you’ll need to look up the steps for each option. My advice? Skip iOS 18.4 for now, especially on older models. The iPhone 16 series seems mostly fine, but for 14 and 15 users, hold off—even for AI perks. Wait for the official release in April; Apple should have this sorted by then.

Additional Notes

After my testing, the iOS 18.4 RC version still exhibits the same issue. For users with dual SIMs, I recommend removing the SIM tray and swapping the primary and secondary cards. After swapping, this can, to some extent, ensure that at least one card works normally. Once it’s functioning, make sure to turn off your VPN, then enable airplane mode for at least 10 seconds and wait. After a while, the signal should fully recover. Note that after updating to iOS 18.4 RC, the IPCC file automatically updates to the latest version 63.0, so the previously mentioned solution of manually updating the IPCC file is no longer applicable.