iOS 27 update mobile network issues

I am facing the same issue in my I phone 16 in India after ios27 update. One is eSIM and second is physical SIM. When both SIM are on, facing network problem and internet also not available. If switch off any one SIM and other works perfectly.

What you describe points to a network/modem-related problem rather than simply an iOS update.

Possible causes include:

• Poor or unstable cellular signal: The modem may work harder when the signal is weak, increasing heat and causing temporary disconnections.
• 5G ↔ 4G/LTE switching: Repeated network handovers can make the modem work harder and occasionally interrupt connectivity.
• Carrier/network issue: A problem with the SIM/eSIM, carrier provisioning, or local network can produce repeated dropouts.
• iOS/modem software issue: A software bug can affect both cellular performance and thermal behaviour.
• Hardware issue: If this happens consistently across different locations and networks, the cellular modem/antenna or related hardware becomes more suspect.
• A particular app: If the problem occurs only with certain apps, background data activity or an app malfunction could be contributing.

A useful diagnostic test: try these one at a time:

1. Switch from 5G to LTE/4G
   1. Settings → Cellular/Mobile Service → Cellular Data Options → Voice & Data → LTE
   2. Use the phone normally for several hours.
2. Compare Wi-Fi and mobile data
   1. If the iPhone remains cool and stable on Wi-Fi but heats up and loses connectivity on cellular data, that strongly points toward the cellular modem/network/SIM/carrier path.
3. Try another SIM/eSIM
   1. If possible, test another carrier's SIM in the iPhone.
   2. Conversely, test your current SIM in another phone.
4. Observe the signal when the failure occurs
   1. Note whether the signal bars suddenly disappear, change to SOS, or remain normal while data stops working.
5. Restart the iPhone and check iOS/carrier settings
   1. Also check Settings → General → About for a possible Carrier Settings Update.

If the phone becomes noticeably hot at the same moment the cellular connection disappears, especially if this happens repeatedly regardless of location or carrier, I would have Apple run hardware diagnostics rather than treating it simply as an app or battery issue.

I had the same issue after updating to iOS 27. Found the FIX. It’s the VPN on your phone. Turn off your VPN or Delete your VPN app. Works perfectly fine after. Then you can reinstall the VPN app.

To fix dual-SIM network dropouts after updating to iOS 27, follow these troubleshooting steps:

1. Disable and Reinstall VPN

Go to Settings > General > VPN & Device Management and completely disconnect or delete any active VPN profiles. Alternatively, remove the VPN app entirely, restart your phone, and then reinstall it.

Verification: Check if cellular data remains stable with both SIMs active after disabling the VPN.

2. Switch Cellular Voice & Data to LTE

Go to Settings > Cellular (or Mobile Service) > Cellular Data Options > Voice & Data and select LTE instead of 5G.

Verification: Ensure your signal bars remain steady and data works consistently on both lines without dropping.

3. Check for Carrier Settings Updates

Go to Settings > General > About and wait for 30–60 seconds. If an update is available, a prompt will appear to install it. If issues persist, contact your carrier to have your physical SIM or eSIM reprovisioned.

Verification: Confirm that your carrier version number matches the latest release and network stability returns.

GOT THE SOLUTION

general>mobile services > voice and data> select LTE or any other options

boom it works 😭

If you're using a VPN, disable it and check if the error goes away. Go to Settings > General > VPN & Device Management and turn off any active VPNs. Disabling a VPN only from the iPhone settings may not completely turn it off. To fully disable it, you need to switch it off from the VPN service provider’s app or remove the configuration profile they installed. Only then is the VPN truly off, which can help if it’s causing issues with cellular or Wi-Fi connectivity.

Do not use a VPN

Ensure the VPN is fully turned off, regardless of whether you are connected. At times deleting the VPN profile may be necessary.

Disable VPN

VPN or proxy connections might prevent your device from contacting the update servers.

Contact the VPN Service provider and disable it for the time being. In some cases, if the VPN server or network is configured to block certain domains or IP addresses, it might inadvertently block Apple's update servers. This could prevent your device from connecting to Apple's servers to download the update. Make sure that the VPN settings do not block Apple-related services.

AT&T released an update late yesterday and is pushing it to users. Please go to Settings > General > About > and wait a minute or two for a notification to appear. If it does, follow onscreen instructions to install. A restart will likely occur. You might want to check with an AT&T corporate store if it’s not been pushed to you yet.

Has the carrier reprovisioned the eSIMs? If not, you can’t be certain. If it were mine, I’d head to one of your carrier’s service locations and ask them to reprovision them. In my experience OTA provisioning often fails.

GOT THE SOLUTION

general>mobile services > voice and data> select LTE or any other options

boom it works 😭

I had the same issue. Found the FIX. It’s the VPN on your phone. Turn off your VPN or Delete your VPN app. Works perfectly fine after. Then you can reinstall the VPN app.

Have you contacted your cellular service provider? In my experience most network issues are resolved through the carrier. Your SIM card(s) may need to be reprovisioned. Please contact your cellular service provider’s support team and see what they say.

I am also facing this issue.

iphone SE (gen 3), worked perfectly fine until "upgrading" to 27.0.1 last night.

Today I have absolutely unusable cellular connection.

Until I disable my dual e-sim. Then everything works just fine.

What a *ludicrous* bug to miss, and to see that it hasn't been fixed in over a MONTH is absolutely unacceptable.

Did AT&T reprovision you eSIM? My son had this issue today and just like last year AT&T reprovision his sim and he was good to go.

Mine was back to normal after iOS27.2 update plus another carrier update

I just found a fix. Delete your VPN app, and re install again

Delete your VPN app and reinstall it again. This fix worked for me.

Delete your VPN app and reinstall it again. This fix worked for me.

Same here on my side in germany.

I already change both E-Sims with no sucsess at all.

When both lines are active no mobile date can be send / recieved.

If one line is switched off mobile datas are available.

I got no solution for this issue instead of waiting for an IOS fix.

... both are new and actual ESims in my case.

And if only one line is active both works without any problem. Just in case you activate both lines the problem exist. In my opinion this is an IOS issue and not a carrier issue!

Many users have been reporting dual SIM cellular issues. Because you have already tried a force restart and resetting your network settings, this is widely tracked as a post-update modem firmware or carrier provisioning bug.

I have the same issue on iPhone14 Pro. I do a lot of steps and it work on ios 27.0. Now after upgraded to ios 27.0.1, the issue occur again.

Luckyly, I do the same steps and the cellular data work again.

Let try:

1. ⁠Deactivate main sim

2. ⁠Go to cellular sim, turn off auto network selection, wait a moment for the list available network show, and select the correct your carrier.

3. ⁠Check to make sure cellular work well.

4. ⁠Turn off the iPhone

5. ⁠Press and hold power button until it go to the recover settings.

6. ⁠Select the 1 option, accept sent analyssis data to apple, and press password. It will not run on my iPhone, but let it at password screen for 10-20s.

7. ⁠Press back and go back to main recovery screen, and press button on top right of the screen to restart

8. ⁠After iphone restart and go back to main screen, wait until cellular sim activate, receive the network signal. Activate the main sim again

It work on my end and not sure if it work on your end. But let try, because it take not much time

Lucky

Just for your information. 27.0.1 didn’t change anything on my iPhone. The bug still exist. No chance to use two eSIMs at the same time. I have to switch one off to receive mobile data! Very annoying!

Hello, I’m facing the same issue on my iPhone 15. I’m experiencing low network signal bars and LTE connectivity issues, both when using dual SIMs and even when using just one SIM.

I’m using a Jio eSIM and an Airtel physical SIM. All the diagnostic tests show no issues, but the problem persists.

I’ve been contacting Apple Support for the past month, and honestly, it has been a frustrating experience. I’ve spoken to more than 20 senior support advisors, and every time, I have to explain the entire issue from scratch. They repeatedly put my call on hold, wasting a lot of my time and energy.

After all this, their final response was that I need to wait for a new iOS update to fix the issue. They said they had escalated the matter to their technical engineering team for investigation.

It’s disappointing that even after a month of follow-ups and speaking with so many senior advisors, there’s still no proper solution or clear timeline for a fix.

Delete your VPN app and reinstall it again. This fix worked for me.

Delete your VPN app and reinstall it again. This fix worked for me.

Delete your VPN app and reinstall it again. This fix worked for me.

This could easily be a bug introduced in the last upgrade. A portion of the modem firmware and software is written by the carriers. There are already community members posting about fixes from their carriers.

I personally faced a similar issue last year with my iPhone 17 Pro Max and AT&T. They tried an OTA reprovisioning and it repeatedly failed. I went into an AT&T store and issue resolved in about 10 minutes.

You can check for any OTA updates by following this path,

iPhone > Settings > General > About > if an update is available from the carrier a notification will appear

Typically the next update from Apple is 4 to 6 weeks after the initial release. I’d talk to my carrier.

Your issue could be. However, there are members reporting similar issues and they are being resolved by their carriers.

Your welcome to contact Apple Support and do diagnostics. A probable step will be reset network settings on your iPhone.

If you can't connect to Wi-Fi on your iPhone or iPad - Apple Support

Diagnostics can be done in person at an Apple Retail Store or at an Apple Authorized Service Provider. You can also contact Apple Support and request remote diagnostics.

If you’re in the US, please call  1-800-MY-APPLE, or outside the US, consult the support articles below. In Canada, call 1-800-263-3394.

Contact Apple for support and service - Apple Support

Genius Bar Reservation and Apple Support Options - Apple

My daughters's iPhone 15 is experiencing the exact same thing. "No service" intermittently -- sometimes for hours, sometimes for days.

Tried everything: reboot cycles, airplane mode cycles, different SIM cards, network settings resets, iphone reset, and have been in calls with Apple Support several times, running multiple tests. Now waiting for a response.

All was well before iOS 27.

Update: I have now updated my iPhone 15 Pro Max (eSIM-only, non-PTA device being used in Pakistan) to iOS 27.1, but unfortunately the same issue is still happening.

The eSIM installs successfully and works normally for 2–3 days, then one SIM profile disappears and the other shows “Invalid SIM” / “No SIM.” I have already tried deleting/reinstalling eSIMs and resetting Network Settings, but the issue keeps coming back.

My iPhone shows “No SIM restrictions”, and the EID, IMEI/IMEI2 and modem firmware are present normally.

I am using the phone non-PTA in Pakistan, so I'm mentioning this in case it is relevant. However, the issue started after updating to iOS 27, and the same problem remains after updating to iOS 27.1.

Has anyone else with an eSIM-only iPhone in Pakistan experienced the same Invalid SIM/No SIM issue after iOS 27, even after updating to 27.1?

Miniature31 wrote:

after iOS 27 update.

Not every issue an individual encounters on their device can be attributed to an iOS update. iOS 27 or later may have coincided with what you are experiencing, but that does not mean the issue was triggered by iOS. Coincidence in timing is not, by itself, evidence of causation.

If the update itself were the root cause, then every device running that same version of iOS would exhibit the identical problem. In such a scenario, the forums would be flooded with countless posts reporting the same malfunction, creating an unmistakable wave of complaints that no one could possibly overlook.

The absence of such widespread reports strongly indicates that the issue is not a general, system-wide problem with iOS 27 or later, but rather something specific to the individual device, its configuration, installed apps, settings, hardware, or another interacting factor.

In short: iOS 27 or later may be a coincidence in timing, but there is no basis to conclude that iOS itself triggered the problem simply because the issue appeared after the update.

I’m having this exact same issue my iPhone 14 Pro Max keeps saying “sim unavailable” it’s only been doing this only as I’ve installed iOS 27. On iOS 26 it was completely fine. I’ve read multiple articles and a lot of users are actually having this same issue I really hope Apple fixes it

Contact Meta support for issues with WhatsApp. It’s the app development team responsible for updating their apps for new carrier and iOS upgrades. In the last month WhatsApp has been updated 17 times. When this happened in iOS 26, Meta took several months to finally fix most of their calling bugs. Their initial advice, which worked for some users, was to backup, delete WhatsApp and download a fresh copy from the Apple App Store.

I have the same issue on my iPhone 16 Pro Max after upgrading to iOS27. When both SIMs are switched on, the primary SIM’s mobile data will stop working and went no signal after that. Once i switched off the second SIM, it will get back normal. I’ve tried different combinations of my physical SIM and eSIM from different telcos/carriers and countries. All gave the same issue. Deleting VPN and switching to LTE doesn’t fix the issue. My iPhone SE 2022 doesn’t have such problem though. Hopefully Apple will provide update to fix the dual SIM bug soon.

iOS 27 Cellular Network Instability – Network Keeps Dropping and Calls Affect Reconnection

Hi everyone,

I’m experiencing a serious cellular network issue on my iPhone 15 after updating to iOS 27.0. Everything was working normally before the update.

The network keeps automatically refreshing/re-registering. For example, the phone may show 5G/True 5G, then suddenly switch to No Service/no signal for 1–2 seconds, then the network comes back again. This keeps happening repeatedly. Sometimes the network may remain available for a short while before dropping again.

There is another unusual problem with calls.

If the network comes back and I immediately make or receive a call, the call connects normally and I can continue talking. Even if the network indicator becomes unstable during the call, the call itself does not immediately disconnect.

However, as soon as the call ends, the cellular network disappears again and the phone returns to No Service. The phone then has to wait until the network automatically comes back before I can make or receive another call.

Because of this, I sometimes have to wait for the network to appear before making a call.

This is not a situation where the phone stays without service for 4–5 minutes. The network can change very quickly — for example:

5G/True 5G → No Service for 1–2 seconds → 5G/True 5G → No Service → network returns again.

I have already tried:

Network Settings Reset

Restarting the iPhone

Completely powering it off

Factory Reset

Testing both 5G and LTE

Testing a Jio SIM

Testing an Airtel SIM

The same issue occurs with both Jio and Airtel, while the Jio SIM works normally in another phone.

I also ran Apple Mobile Diagnostics multiple times. Every time, it reported:

“Diagnostics detected a software issue.”

The diagnostic screen showed iPhone Hardware as passed/green, while Mobile Service was flagged.

I have also noticed unusually high battery drain with very little usage.

Has anyone else experienced this exact behavior after updating to iOS 27.0, especially the part where an ongoing call can remain connected but the cellular network disappears again immediately after the call ends?

Could this be related to the iOS 27 cellular/modem software or network registration process?

Phone 15 Pro Max – SIM/eSIM issue after iOS 27 update

I have an iPhone 15 Pro Max that was working normally before updating to iOS 27. After the update, the SIM/eSIM works fine for around 2–3 days, then suddenly one SIM disappears and the other shows “Invalid SIM.”

I’m using a travel/data eSIM, and the phone is carrier unlocked (“No SIM restrictions”). The EID, IMEI/IMEI2 and modem firmware are all showing normally.

When the issue occurs:

• 
  
• One line disappears.
• 
  
• 
  
• The other shows Invalid SIM.
• 
  
• 
  
• Control Center shows Invalid SIM / No SIM.
• 
  
• 
  
• Deleting/reinstalling the eSIM temporarily changes the SIM entries, but the problem returns.
• 
  
• 
  
• I have also Reset Network Settings, but it did not permanently resolve the issue.
• 
  
• 
  
• I eventually deleted all eSIMs, but the phone still showed the same Invalid SIM / No SIM behavior.
• 
  

The strange part is that everything works normally for 2–3 days before failing again, and this started only after upgrading to iOS 27.

Has anyone experienced the same intermittent Invalid SIM/No SIM issue after iOS 27 on iPhone 15 Pro Max, and found a permanent fix?

There are many online reports from people who brought iPhones with this issue to the Apple Store and were told that it was a hardware issue, which is exactly what the device diagnostics say.

I doubt that this is a hardware issue for the following reasons:

1. The issue occurred right after installing iOS 27 update, and it wasn't just my phone; many other people reported the same trigger.
2. I just installed iOS 27.2, and suddenly, cellular service worked again.
3. Then, I put my phone on charge and didn't touch it for a while, and the problem occurred again.
4. I asked Claude to investigate before and after, and he found that the cellular modem goes to sleep after a period of inactivity. However, it can't be woken up by the system next.

If I can see cellular service working well after the iOS 27.2 upgrade, and then it goes to sleep and can't be woken up, it's probably not a hardware issue.

So, my iPhone 13 Pro has no cellular service again.

Neither the physical SIM nor the e-SIM works.

I also tried to open iOS Settings > General > About > and there is no "Carrier Settings Update", so it's not a solution.

This update is a nightmare. I usually avoid updates, but I don't know why I opted into these iOS 26.7 and then iOS 27 updates. Now I'm facing the same issue: no network and no calls. I've tried almost every solution I could find online.

I really hope Apple releases a fix for this soon.

The moment I updated the ios to 27 both my sims stopped working together. If u switch off one of them, the other works fine. I have since been trying everything in my capacity to fix this. I have contacted apple support, did everything they asked me to do.I have even visited service centres, where apple has only trained their engineers one thing. Any problem you are facing, we will update your software. If that resolves your issue, its fine. If not, that’s yours to handle. We do not know beyond this. So now, after trying everything and spending money on something which was not even my fault, m still stuck with the issue with no help at all. I really hope apple comes up with a solution asap!!

Same here, in Madrid, Spain. Since I updated to ios 27 calls get’s finished sudde nly or I can not call. Also data is impacted, really slow speed in carrier data mode, wifi works fine.

Sol Apple Store says is my carrier, but I know lot of people facing same issue since they updated. Shamefull.

Not resolved after complete restore, configs and data. Iphone 17. Apple does not provide any solution. Same SIM card working fine in Redmi Note 14. Shameless. Xiaomi 1 - Apple 0 🙂

edit: I don’t use any VPN

I am having an issue with my iPhone 17 Pro Max in Kosovo after updating to iOS 27.

I am completely unable to make or receive cellular calls, even though my 5G mobile data and SMS text messaging are working perfectly.

My carrier, Vala, confirmed that everything is fine on their end and stated that this is a bug with the iOS 27 update. I have already tried standard troubleshooting steps, but nothing has resolved the issue. The iOS 27.0.1 update did not fix it either.

Yes I have contacted service providers multiple times regarding this issue and they said there is no issue from there end and it could be due to iOS update.

I have a iPhone 15 pro max. Updated to iOS 27, and since then my WhatsApp calls drop, I keep getting messages saying ‘poor connection’. I tried everything, resetting the network settings, resetting the phone, even having problems with wifi connection, and social media posts are loading slower or buffering. Any advice please??? Thank you

I am also facing same issue. I have tried all the possible ways even though re-installed e-sim but nothing helps after updating to ios 27.

If any help would be valuable.

I am using iphone 14

Thanks in advance

Ios27 update on iPhone se3(2022)

result is Meta application like Facebook Instagram whatsapp tell Connect to internet , in Fact not possible to use it on wifi or 5g it’s the same with Spotify, only duolingo works perfectly is it due to Meta apps or iOS 27?

After the ios 27 update my cellular network signal problems

from the past 3 days no signal i tried every trick

now i purchase the new android phone and convert the e-sim to a physical sim

waiting……… for new update 😂😂😂🙈

iPhone 15 Pro Max (eSIM-only) – SIM/eSIM issue after iOS 27

My iPhone 15 Pro Max is an eSIM-only model and was working normally before updating to iOS 27. After the update, my eSIM works normally for around 2–3 days, then suddenly one eSIM disappears and the other shows “Invalid SIM.”

The phone is carrier unlocked (“No SIM restrictions”), and EID, IMEI/IMEI2 and modem firmware are all present normally.

When the issue happens, Control Center shows Invalid SIM / No SIM. I have tried restarting, deleting/reinstalling eSIMs, and Reset Network Settings. These actions may temporarily bring the SIM entries back, but the problem returns after a few days.

I have tested with newly issued eSIM profiles as well, so it doesn’t appear to be a single faulty eSIM.

The strange part is that the eSIM works perfectly for 2–3 days and then suddenly stops, and this started after updating to iOS 27.

Has anyone with an eSIM-only iPhone 15 Pro Max experienced this intermittent Invalid SIM / No SIM issue after iOS 27? Looking for a permanent solution or confirmation of whether this is an iOS/modem issue.

Apple very bad this is ridiculous update ios 27 it’s been 1month there is no response from apple after update dual sim problem started Internet doesn’t work when both sim are on and after sec 1sim network goes away When one sim turn off den only the Internet work … very 3rd class update from apple .. I thing 6k android phone work better in dual sim then this …. When apple will response.

I am also facing the same issue. Mobile data doesn’t work with dual sim active. It works only if I disable one the sims. Tried everything including reset all settings and delete the old ones. Nothing worked. Having 14 pro max

My 5g not working. 5G Is worked in my phone before I Update to iOS 27. First of all I think maybe there is a 5g maintenance wrok in my area. But when I cross check Other devices with same provider They use 5G with no Trouble. Even when I check my Sim Card In Another phone 5G network Work perfectly. I am facing the problem from across one week. Please fix it. But this Problem only happen in my area, When I go to the main Road, then the 5G work perfectly.

thanks a lot. It worked for me too. But unnecessarily after doing factory reset and deleting all settings. Also lost my whats app data in the same. Wish would have seen your message earlier.

Thanks again

This is simply IOS issue, since SIM working well with other phone. Why mentioning carrier issue?

I tested both SIM other phone and it’s working perfectly fine. Accept when active both SIM at the same time, issue will persist. When disable one SIM and it just working fine for other.

how to called if it not IOS issue?

IOS should fine the resolution for version 27, since this is very annoying.

Hi Pratik,

Have you got a solution?

Even I’m facing the sane issue since 13th October.

Like you, I’m also using a Jio eSIM and an Airtel physical SIM. All the diagnostic tests show no issues, but the problem persists.

I even visited the service centre yesterday, they also didn’t not get any solution.

Same issue, started right after the upgrade to iOS27, my carriers don't see any issue in their end, so I guess it must be iOS.

I got two carriers in my iphone ... Vodafone and Telekom ... i use new ESims of both carriers ...

There is actually no update available from carriers ...

I have the same issue with eSIM orange after update problème de connection of cellular data lent and stop all time

my networks keeps refreshing and the internet doesn’t work. Idk how I’m supposed to work now

Even i am the one facing these problem and

Since I installed the 27.0 update on my iPhone 14 Pro, I can’t make or receive calls with my SIM card.

same problem here too: AT&T and iphone 17 everything was fine until ios27 update. Internet comes and go and can't make any phone call.

I’m also facing the exact same issue in my iPhone 15 plus post ios 27 update. Can anyone give us a temporary work around?

Yes. Same issue with my device as well.

The strange thing is also that an iPhone 18 Pro Max with iOS 27 has all these issues, but an iPhone 12 Pro with iOS 27 and also dual SIM configuration with same carriers has no issues at all.

My iPhone is having problems with network since I have updated the iOS 27

I don’t use VPN

I am also facing the same issue, I tried to change sim that is also having same issue.

I have AT&T, and ever since I updated my phone to the new software update, my messages take forever to send. I’ve already tried all the troubleshooting steps, but the issue is still happening.

Perfect testing on all scenarios, Apple needs to fix it ASAP.

The same situation with my phone.

iPhone 13 Pro, same cellular network issue after iOS 27 update (or iOS 27.0.1, I can’t say for sure). Carrier Vodafone.

Any fix coming for this issue, this is causing lot of issues.

Yes single line working

It's nonsense if they don't fix these problems quickly; we're constantly having issues with every update. Apple's reliability is starting to decline.

what a ridiculous answer in light of the facts presented by hundreds of users.

Facing problem in wifi and network connection after update ios27.2 in my iPhone 14 pro max

I am facing the same issue but i ahave iphona 13 with only 1 sim card but i couldn’t solve the problem i used everything