iOS 27 update mobile network issues

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.

GOT THE SOLUTION

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

boom it works 😭

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.

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.

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!

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 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.

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.

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

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!!

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

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 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.

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.