iOS 26.4 causing serious issues (battery drain, Wi-Fi problems, overheating)

You aren't speaking with Apple here. This is a user to user only forum, which Apple neither participates, nor reads for user feedback.

While I have no doubt you are having issues, it's not likely caused by iOS 26. There are millions upon millions of people out there with iOS 26 who aren't having any issues. Like me, for example. All of our devices are updated to iOS 26, Apple WatchOS 26, iPadOS 26, MacOS 26, with zero issues.

What we need to figure out is why you are having issues.

Things which can cause issues like you're having could be a failing battery or lack of free memory. You didn't tell us what model iPhone you own, but if it's more than 2 years or so old, the battery could be failing. Open Settings > Battery > Battery Health - what is the current health listed there? If 80% or less, your battery is failing and needs to be replaced at your Apple Store Genius Bar.

Now for storage, open Settings > General > iPhone Storage - how much space do you have left on the phone. If you have less than 12GB or even lower, you need to delete things on your phone to free up space, such as Photos, Videos, Music, Apps, Messages, Email, etc.

Do you have a VPN installed on your iPhone? VPNs cause all sorts of connectivity issues and they aren't needed unless one is required by your school or employer. If you have a VPN on your phone, remove the VPN profile and any associated Apps, then follow the procedure I'm including a link to below.

Finally, after you updated your phone, did you or do you ever Force Restart it? I Force Restart after every iOS update and this procedure is recommended when you experience issues --> Force restart iPhone - Apple Support

D_K_S wrote:

Ever since the 26.4.2 update my iPhone battery drains fast and constantly over heats and I’m not the only one having these problem!!!

“The iOS 26.4.2 update has been reported to cause overheating issues on iPhones. Users have noted that after updating, their devices experience significant temperature increases during normal use, alongside other problems like battery drain and unstable Wi-Fi connections”

🤬

Reported where? All of our devices are running iOS 26.4.2 and none of them are having any heating issues of any kind. It's common for heating to happen immediately after an update as a phone needs to spend what can be days, depending on how much data is on the device, to reindex the millions of bytes of data. Another cause can be a battery which is failing. If you open Settings > Battery > Battery Health - if the battery health is close to, at or below 80%, the battery is failing.

As to Wifi connectivity issues, is there a VPN on the phone? VPNs don't provide the security people have been led to believe they do, in fact, quite the opposite. VPNs do, however cause Wifi connectivity issues, so if you have one, get rid of it unless required by a school or employer.

Another issues can be available memory on the device. In Settings > General > iPhone Storage - how much free space is available? You should strive to have at least 10GB - 12GB available at all times. If storage is low, the phone can't operate optimally.

Updates don't typically cause connectivity or heating issues. There are too many other factors at play which need to be considered. There are literally hundreds of millions of people on iOS 26.4.2. Out of that number, there will always be a small percentage of users who have issues. That doesn't mean the vast majority of people on iOS 26.4.2 are having issues. If this was a significant issue, this forum, the most visited forum for all things iPhone would be blown up with people complaining, but it's not. The Tech Press would be all over this, but they're not.

"Yes, I have already submitted an official complaint to Apple and also had my device checked at a service center. I did not experience these issues on iOS 18, but they started after updating to iOS 26. The service center also mentioned that the problem is likely related to the update."

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Overheating After an Update:

IF App insists that it will be fixed in "future updates", then you may want to wait it out. In regard to the grey screen, there any bulging in the iPhone? If so, then that would indicate that the battery is corroding, and you should get this serviced, as it has become a Health Hazard.

Clear the System Data:

System Data is caches that are created by applications for embrace of usages, so that they can open quicker, and operate for sufficiently. None of this is needed. So, see about creating it all. Many out there don't realize it, but it can take up extensive amounts of storage. Use my User Tip: How to Clear "System Data" in your iPhone's Storage: - User Tip

ChisolmLee15 wrote:

Regarding VPN, I find it handy for changing "my" WAN IP address - as a go around for some website challenges (Google's rCAPTCHA, Cloudflare, and some video sources).

Most will find that some simply interfere with network connections and prevent access to many servers. Apple even includes a Support Article for network issues with the first step to uninstall a VPN. If it is working for you so far, then great, and if you start experiencing Networking trouble then you will know that the first think to do is uninstall the VPN.

If your device has network connectivity issues, check for VPN and other third-party security software - Apple Support

For occasions of major iOS updates for iPhones, I fold a clean wash cloth do it is 2 layers and wrap a small "blue ice" pack (Walmart). I set the iPhone's back surface on that homemade cooler.

That keeps the phone from getting too hot.

OK. The only time you needed to be concerned that your phone is too hot is when it trips the heat sensors and you see the thermometer on the screen telling you the device is too hot and needs to cool down.

Regarding battery changes, "Apple Genius" is probably good for many iPhone users, but you can find some repair shops online, that do have very good techs and service.

Terrible advice if you want Apple to provide further service on your phone. If the provider is not an Apple Authorized Service Provider that previously serviced a phone, then Apple has refused to further service the phone. If you got an old device and you could care less if it works again and have no plans to ask Apple for service, then certainly that would be an option. If a Battery replacement is not a genuine Apple part, users have reported poor usage performance and premature failures. There are also many repair scams online, so navigating the land mine may be a challenge.

Regarding Apple's interest in this discussion forum, there are some Apple employees who keep an eye on this place - that is owned and managed by Apple.

Only Apple moderators make sure posts comply with the Terms of Use for this Support Site and follow the Community Etiquette Guidelines. Beyond that Apple will note post for any Support Question and posts are not forwarded to Apple for feedback. Many people expect that Apple is going to respond to a question or read their post for consideration of a new feature and that is not the case. Users are directed to use the Feedback link when appropriate where Apple will then read what they post.

Ever since the 26.4.2 update my iPhone battery drains fast and constantly over heats and I’m not the only one having these problem!!!

“The iOS 26.4.2 update has been reported to cause overheating issues on iPhones. Users have noted that after updating, their devices experience significant temperature increases during normal use, alongside other problems like battery drain and unstable Wi-Fi connections”

🤬

I installed it yesterday and it suddenly was overheating and it could not be used for some time, a popup showed up telling me that. The phone was really hot. Battery drain was extraordinarily high, battery was dead after 3,5h after using HERE navigation system and a couple of calls

Honestly, I'm having the same issue since updating to 26.4.

I have an iPhone 17 Pro, battery health at 100%, I'm doing the optimized charging (up to 80%), etc. I noticed since upgrading to 26.4 that without even touching my phone, my battery is draining very fast!

Today I was using it very lightly, and it went from 40% to 15% in just a couple of hours. Wasn't doing that before.

I'm updating to 26.4.1 as I type. Hoping that takes care of the issue.

I keep my iPhone wall socket- charger plugged in, as often as I can.

For occasions of major iOS updates for iPhones, I fold a clean wash cloth do it is 2 layers and wrap a small "blue ice" pack (Walmart). I set the iPhone's back surface on that homemade cooler.

That keeps the phone from getting too hot.

The iPhone are encased within protective covers. So, that case plus cotton wash cloth layers = no direct contact between iPhone back and "ice."

Regarding VPN, I find it handy for changing "my" WAN IP address - as a go around for some website challenges (Google's rCAPTCHA, Cloudflare, and some video sources).

Regarding battery changes, "Apple Genius" is probably good for many iPhone users, but you can find some repair shops online, that do have very good techs and service.

Regarding Apple's interest in this discussion forum, there are some Apple employees who keep an eye on this place - that is owned and managed by Apple.

“reindex the millions of bytes of data Or in short, a few tens of gigabyte”

———-

?

I think you mean “a few tens of thousands of megabytes”, or, put another way, “tens of gigabytes”.

Megabytes is in the millions; so, it’s in the billions that you’ve reindexed. So, if you only reindexed less than a gigabyte of data, that doesn’t seem plausible, as the macOS, itself, has around 15 GBs of its own data.

Great news, I hope it arrives quickly

Sadly 26.4.1 did not solved wifi issues on my iPhone 17. Almost impossible connect to home wifi, quickly battery draining and overheating

reindex the millions of bytes of data

Or in short, a few tens of gigabyte