"Parasitic cellular data drain" iPhone XS after iOS 18.x installed

[robbinia]

On July 7th I did a clean re-install of iOS 18.5 and then updated to the dev beta 3 of iOS 26 and since then the consumption of cell data has been really low. I started iOS 26 with none of my apps installed except My Data Manager and had nothing running for a few days then gradually reinstalled my apps and switched on location services, etc. It's used 192mb of cell data for system services since the update (avg 15mb/day) which is a massive drop compared to how it was on iOS 18.

For the past few days it's been back running as a 'normal' iphone & I'll definitely be updating to the public beta of 26 if/when it comes out this week as it seems way better running the new iOS (even in beta form) than 18.

 

[Newtons]

It’s bad enough all these tech companies make a lot of money from selling our data.

I hope they aren’t wasting our data somehow to spy on us, and then making us pay for the data consumption (minus the unlimited data plans)

 

[Neebee]

I can't believe the issue still isn't "recognized" by Apple. Just today I got hit with 120 MB+ drain after enabling cellular data. Sometimes, I can go for hours without the drain. The trigger seems to be whenever the iPhone "calls home". It sucks there's not much info online but I get it. Most people have insane amounts of data so it's not an issue. But if you're using a travel eSIM you need to pay more for a higher data bucket.

 

[Neebee]

On July 7th I did a clean re-install of iOS 18.5 and then updated to the dev beta 3 of iOS 26 and since then the consumption of cell data has been really low. I started iOS 26 with none of my apps installed except My Data Manager and had nothing running for a few days then gradually reinstalled my apps and switched on location services, etc. It's used 192mb of cell data for system services since the update (avg 15mb/day) which is a massive drop compared to how it was on iOS 18.

For the past few days it's been back running as a 'normal' iphone & I'll definitely be updating to the public beta of 26 if/when it comes out this week as it seems way better running the new iOS (even in beta form) than 18.

It's bizarre. My spouse's iPhone 13 has no issue and the settings aren't as conservative as mine. My XS can't upgrade to iOS 26. My guess is Apple doesn't care about us who have unsupported phones like the XS.

 

[ManuCH]

Honestly, you use a museum phone and you are on some plan from the 1980s. Maybe you should get an Android 😉

 

[colin773]

I came here to thank OP because I've been wrestling with the same issue for ages. It's not a carrier bug. It's not OP's old phone. OP isn't imagining it. My own issue, which fits OP's description exactly, cost me $90 in fees last month for exceeding my data plan. Unlimited plans don't make sense for all users on all carrier networks, and for people like me and OP, this issue is a serious problem.

I've been to the Apple Store twice to present my own detailed findings while troubleshooting this, only to stump the Support supervisor/head "Genius" and be told there's nothing else they can do for me. I would reach out to Apple Support by chat or phone, but OP's own experience doesn't inspire much confidence.

The steps OP shared from their own troubleshooting and the deleted Reddit post have been helpful to me so far in identifying updates.cdn-apple.com as the main culprit in my own runaway data use. I only blocked it moments ago using Proxyman, so it remains to be seen if it's totally effective in solving my issue. I anticipate it will be and plan to report back here.

 

[alexanpob]

Hi everyone, I've been having a similar issue for years with various iPhones. They all run pretty sluggish, and I can't figure out what's going on. Right now, I have a new 17 Pro, and it dies completely in three days, just sitting on the table. I have iCloud, but I specifically disabled everything to prevent it from syncing. There are no apps, just basic Apple software. I've noticed that Push notifications are using a lot of data—about 50 MB per day. But what's sending so many Push notifications if the phone doesn't have anything on it? Has anyone else encountered something similar and found a solution? It feels like the phone is constantly sending something somewhere, and it's related to Apple's servers and my iCloud.

 

[ManuCH]

Hi everyone, I've been having a similar issue for years with various iPhones. They all run pretty sluggish, and I can't figure out what's going on. Right now, I have a new 17 Pro, and it dies completely in three days, just sitting on the table. I have iCloud, but I specifically disabled everything to prevent it from syncing. There are no apps, just basic Apple software. I've noticed that Push notifications are using a lot of data—about 50 MB per day. But what's sending so many Push notifications if the phone doesn't have anything on it? Has anyone else encountered something similar and found a solution? It feels like the phone is constantly sending something somewhere, and it's related to Apple's servers and my iCloud.

Even if getting no notifications, the iPhone needs to keep the connection to Apple's push notification service (APNs) alive all the time. That in itself uses data.

 

[alexanpob]

Even if getting no notifications, the iPhone needs to keep the connection to Apple's push notification service (APNs) alive all the time. That in itself uses data.

I understand that it's connected to the network and transmitting some data. I don't mind the traffic, but it's obviously draining the battery, and I don't know how to stop it. A fully charged phone runs out of power in 2-3 days.

 

[ManuCH]

I understand that it's connected to the network and transmitting some data. I don't mind the traffic, but it's obviously draining the battery, and I don't know how to stop it. A fully charged phone runs out of power in 2-3 days.

That is expected behavior and cannot be stopped. A fully charged phone will run out of power in 2-3 days unless you completely disconnect it from the network (by putting it to airplane mode).

 

[alexanpob]

That is expected behavior and cannot be stopped. A fully charged phone will run out of power in 2-3 days unless you completely disconnect it from the network (by putting it to airplane mode).

This is unhealthy behavior for iPhones. My iPads with the same iCloud account sit plugged in for weeks, three to four weeks. Okay, they have a bigger battery, but they also sync and have apps installed. But here, nothing. Moreover, if I reset the phone, set it up without iCloud, and connect it to the network, the battery drain is minimal; the phone can last for two weeks. But as soon as iCloud is installed, the drain becomes simply catastrophic. Unfortunately, this is abnormal behavior. I don't understand what's wrong with iCloud and why the drain is so insane in my case.

 

[Neebee]

The parasitic drain is still happening at high volumes over over 100+MB at a shot with General Services (even when connected to Wi-FI) and I've noticed mapping services using it to even though I'm not connected to maps. I really have to wonder if it's a software bug in the XS Max series because obviously third party apps can't be using Apple's System and General Services.

 

[colin773]

The parasitic drain is still happening at high volumes over over 100+MB at a shot with General Services (even when connected to Wi-FI) and I've noticed mapping services using it to even though I'm not connected to maps. I really have to wonder if it's a software bug in the XS Max series because obviously third party apps can't be using Apple's System and General Services.

The issue affected my iPhone 16 Pro, too.

It was little relief to find that updating from iOS 18.7 to 26.5 stopped the General Services data drain.

 

[Neebee]

The issue affected my iPhone 16 Pro, too.

It was little relief to find that updating from iOS 18.7 to 26.5 stopped the General Services data drain.

This is what makes no sense. I do think location services plays a minor role though.

Could all this be an account sync issue rather than an issue isolated to the device ? For me, this all started after replacing my iPhone under warranty (exception basis). Meanwhile, the privileged and antagonists like @ManuCH refer to perfectly functional devices as museum pieces.

If I'm going to have to reinstall numerous apps, folders, and configure the layout I'm seriously consider moving to Android rather than dealing with Apple support and fighting an uphill battle to have this escalated to an engineering specialist to push debugging software and determine what's exactly going on if there's a likelihood it'll be replicated on a new iPhone.

 

[ManuCH]

This is what makes no sense. I do think location services plays a minor role though.

Could all this be an account sync issue rather than an issue isolated to the device ? For me, this all started after replacing my iPhone under warranty (exception basis). Meanwhile, the privileged and antagonists like @ManuCH refer to perfectly functional devices as museum pieces.

If I'm going to have to reinstall numerous apps, folders, and configure the layout I'm seriously consider moving to Android rather than dealing with Apple support and fighting an uphill battle to have this escalated to an engineering specialist to push debugging software and determine what's exactly going on if there's a likelihood it'll be replicated on a new iPhone.

Privileged and antagonists 😂😂😂 go on, it's hilarious. I guess we all are privileged just by the fact we can afford iPhones, right?

But on a more serious note, I don't think Apple will ever solve this, and even if you try to have it escalated to engineering, I don't see this as being solved, realistically. I don't know if Android behaves better, but it's probably worth giving it a try.

 

[colin773]

I agree ManuCH's replies on this have been antagonistic and unhelpful, not least because the age of your hardware is irrelevant. But that doesn't mean I'm optimistic about a resolution from Apple. And I'm not personally optimistic about a better all-around experience on Android just because I've been burned by Apple here.

Overall I'm unhappy and frustrated by this experience, but I don't feel I have recourse. My best hope is a class action suit someday, because this issue has probably cost me close to $1,000 in data plan overage fees over a year or two. I haven't yet tallied it up from phone bills, and I don't know if I'll ever know for sure how many of those were directly related to this issue vs. WiFi Assist using cellular data overnight when I'd expressly disabled it at home.

I only anticipate a suit not because I'm vindictive and litigious, but because I've been included on what feels like a lot of suits against Meta where I'd lost far less. But I think the classes in those suits were enormous, so who knows. The issue here seems to affect a sliver of the iOS user base.

In the grand scheme of things, I have to let it go and move on to hold on to what little sanity I have left.

 

[FeliApple]

An update, I said back in June 2025 that my iPhone 16 Plus had used 459 MB for general and 1.08GB for Siri.

It’s July 2026, and system services has used a total of 15.1 GB of the total used by me, which is 71.8 GB (yes, 71.8 GB in about 16.5 months of ownership).

Siri rose to 6.82 GB, or about 5.74GB in 13 months, for a monthly use of 441MB. Honestly, the system using 915MB/month is rather significant to my 8GB data plan, but I don’t use it enough to care.

Still, 21% of my entire data usage is iOS itself, which is beyond ridiculous.

 

[ManuCH]

I agree ManuCH's replies on this have been antagonistic and unhelpful, not least because the age of your hardware is irrelevant. But that doesn't mean I'm optimistic about a resolution from Apple. And I'm not personally optimistic about a better all-around experience on Android just because I've been burned by Apple here.

Overall I'm unhappy and frustrated by this experience, but I don't feel I have recourse. My best hope is a class action suit someday, because this issue has probably cost me close to $1,000 in data plan overage fees over a year or two. I haven't yet tallied it up from phone bills, and I don't know if I'll ever know for sure how many of those were directly related to this issue vs. WiFi Assist using cellular data overnight when I'd expressly disabled it at home.

I only anticipate a suit not because I'm vindictive and litigious, but because I've been included on what feels like a lot of suits against Meta where I'd lost far less. But I think the classes in those suits were enormous, so who knows. The issue here seems to affect a sliver of the iOS user base.

In the grand scheme of things, I have to let it go and move on to hold on to what little sanity I have left.

I would like to apologize if my comments came over as antagonistic, I was trying to be funny.

I see where everyone here is coming from. By my own experience I can say that Apple likely is not building their iOS with non-flat data subscriptions in mind. You can see this by how iOS behaves. People have issues here all the time when they're abroad roaming (and therefore data is not flat).

Now, is this good? No, it definitely isn't. Do I see this changing anytime soon? Also no. It's one of the areas where Apple has been lacking in my opinion. The "care to detail" lacks when it's about optimizing data usage (or storage, really).

If I was one of those affected by parasitic data usage and I was bothered by it, I'd probably switch to Android and hope that their customization allows me to more granularly fine tune what my phone does.

Apologies again if my way of being funny wasn't funny. I see the issue. I just don't think a solution is realistic at all.

 

[FeliApple]

I would like to apologize if my comments came over as antagonistic, I was trying to be funny.

I see where everyone here is coming from. By my own experience I can say that Apple likely is not building their iOS with non-flat data subscriptions in mind. You can see this by how iOS behaves. People have issues here all the time when they're abroad roaming (and therefore data is not flat).

Now, is this good? No, it definitely isn't. Do I see this changing anytime soon? Also no. It's one of the areas where Apple has been lacking in my opinion. The "care to detail" lacks when it's about optimizing data usage (or storage, really).

If I was one of those affected by parasitic data usage and I was bothered by it, I'd probably switch to Android and hope that their customization allows me to more granularly fine tune what my phone does.

Apologies again if my way of being funny wasn't funny. I see the issue. I just don't think a solution is realistic at all.

Yeah, those two issues are so utterly ridiculous that the fact that they haven’t been solved is beyond laughable.

iOS using this much data is ridiculous (I checked a family member’s phone and the system was using about 2.4 GB of cellular data per month, they’re lucky they barely use data because their plan is like 6 GB/month, they’re never noticed because they don’t use it) and iOS’… what? Decade-old issue with storage? More than that? I don’t even know how many years ago this started really… well, in any case, it is ridiculous that the infamous and nefarious system data keeps ballooning and Apple has never implemented a way to get rid of it or fixed the inexplicable ballooning issue.

Especially considering that they’ve sold, say, 64GB iPads as current until 2022, and they’ve sold the 9th-gen iPad until 2024.
I have a 64GB iPad Air 5 (M1). The only reason I’m fine is because I’m running iPadOS 15. You may be aware of this, but iPadOS 26 uses and requires FAR more storage, with people reporting up to 47GB of use. For me, iPadOS and System data combined use about 10 (and I have 40GB free), but this issue is also unacceptable.

Sadly, like you said, we are going to have to get used to both, because it doesn’t seem like a fix is coming.

 

[ManuCH]

Yeah, those two issues are so utterly ridiculous that the fact that they haven’t been solved is beyond laughable.

iOS using this much data is ridiculous (I checked a family member’s phone and the system was using about 2.4 GB of cellular data per month, they’re lucky they barely use data because their plan is like 6 GB/month, they’re never noticed because they don’t use it) and iOS’… what? Decade-old issue with storage? More than that? I don’t even know how many years ago this started really… well, in any case, it is ridiculous that the infamous and nefarious system data keeps ballooning and Apple has never implemented a way to get rid of it or fixed the inexplicable ballooning issue.

Especially considering that they’ve sold, say, 64GB iPads as current until 2022, and they’ve sold the 9th-gen iPad until 2024.
I have a 64GB iPad Air 5 (M1). The only reason I’m fine is because I’m running iPadOS 15. You may be aware of this, but iPadOS 26 uses and requires FAR more storage, with people reporting up to 47GB of use. For me, iPadOS and System data combined use about 10 (and I have 40GB free), but this issue is also unacceptable.

Sadly, like you said, we are going to have to get used to both, because it doesn’t seem like a fix is coming.

Exactly. Personally, my main gripe is storage ballooning overall, and the related inability to manually delete cache (which can be easily done on Android). Also the way iCloud Photos handles its library is an absolute joke. I have a library with around 100k photos, and instead of being able to purely stream them (like Google Photos does), it has to sync the whole thing, and even with "optimize storage" turned on, it takes hours if not days every time when setting up a new device.

So really, this whole area, along with the data use department, would need a complete overhaul IMHO.