Wifi drops when phone is locked after 10.3.3 update

Did you even read the last, bolded and italicized part of that quote from the developers document? The minute the screen locks, ALL wifi access apps are considered "idle" and lose their wifi connection. That is exactly how it has always happend, how it is supposed to happen, and how iOS is coded to work.

Persistent wifi connections require the device have the screen unlocked, or be connected to an external power source (the connection of an external power source forces iOS to suspend the wifi time-out function altogether, keeping the wifi radio powered on all the time, until the power connection is disrupted and battery power resumes)

Rayclod, I can't answer your 1-3s, but I can tell you this, from personal experience:

I recommend following Silverteem's suggestion. I did, and it solved the problem for me. Maybe the "problem" is the way iOS and the iPhone are supposed to work, but just because something does what it's supposed to do doesn't mean it's not a problem for many users. Silverteem's suggestion "fixed" or solved the problem for me, and I didn't have to take the time and effort to jump through all the hoops of factory resetting, backing up, restoring, etc.

Just disable "Auto-Login" and see if that does the trick. It did for me. I did it five (5) days ago, and the "problem" has disappeared completely. It has not come back a single time since then. (Just tested it again this very moment, and the WiFi icon appeared immediately upon waking my phone, no delay and no 4G icon for the 3-6 seconds that it used to appear before I disabled Auto-Login.)

I have iPhone 5C latest update for it is iOS 10.3.3 and iPhone X latest update for it is iOS 11.2

I had the same issue which you have described in your Description of your Question

So I Restored my iPhone 5C as NEW and I Pinged it's IP when Locked ; After a few seconds not minutes the PING response gave failed messages, but the minute I pressed the Home Button or Lock Button the Wi-Fi symbol was there instantaneously and the PING gave a Successful response. (Note that the Entire time the iPhone 5c was being PINGED)

THIS Restore as New fixed the Problem of "The Time from Waking the iPhone 5C to the Time it takes to Re-Connect to Wi-Fi"

But on iPhone X when I Tap the Screen or Wake it using Hardware buttons the Wi-Fi Symbol shows for a very very brief instance and then Disappears and then takes 2-3 seconds not nano seconds to Re-Connect ! (I have tried "Restore as New" and putting into DFU and Restore)

The PING on iPhone X shows that even after waking the Device it doesn't Connect INSTANTLY which clearly Verifies the above scenario!

This is why only on iOS 11 people in my opinion are complaining because the Delay is too long !

So I believe the issue is with iOS 11 and DISCONNECTING Wi-Fi on certain if not All iOS Devices and NOT putting it in Sleep State !

Note According to Apple Wi-Fi should be DISCONNECTED if the Device is not being used after a period of around 30mins

No. You should see both "Auto-Join" and "Auto-Login." Only disable/toggle off "Auto-Login." That was Silverteem's recommendation, and it worked perfectly for me. Leave "Auto-Join" enabled. Disable "Auto-Login."

I had an issue with my iPhone 5C and it had Auto-Join .

But the internet used to disconnect when turning off.

I fixed it ; the steps are:

1) Connect to iTunes

2) Tap on Restore

3) Set Up iPhone as NEW

Do not Restore from Backup

KiltedTim,CoolStoryBob

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I've tried another router and it works perfect. Now, as for me, there is no iOS bug, but router bug.

iPhone shouldn't drop wi-fi when locked, it shouldn't miss notifications, it is not supposed to work as you saying, you are wrong.

I asked Apple Support to explain the problem. They said, that notifications must come when iPhone is idle, it can't disconnect wi-fi. They advised me to restore iPhone and set up as new, but I already did and it didn't help, after this they recommended try another router. So I find an old cheap TP-Link TL-WR741ND and it works perfect, no disconnects, no missed notifications, yeah.

You can say what you want, it doesn't even matter to me, thanks.

After the last update to ios11 the problem solved!

I read everything you have said. The fact is, the only things that you have left to do, since you believe this is a phone issue, is to restore the device to factory and set it up as new. Then add your content back to the device individually, one at a time. Add you wi-fi calling app, then test it. Then add your mail and test it. I know not everything is working the way it is supposed to, but when you are not doing anything on the phone and it is locked and not connected to power, then it will not be connected to wi-fi. The fact that it is locking while you are in your call means something is wrong, and I believe it to be that app. Talk to the developer. Barking at us is not going to do anything for you. The app developer needs to determine its compatibility. Not you, me, Apple, or anyone else here.

That demonstrates that the Wi-Fi icon is on. It does NOT demonstrate that Wi-Fi was on when the phone was locked. The real test is to ping the phone when locked and unlocked. I've posted this before, but here it is again:

• Open Settings/Wi-Fi and tap on the i next to the network name
• Write down the IP address
• Open a Terminal window in Mac OS (or a CMD window in Windows)
• Mac: Type "ping <the IP address you wrote down>"
• Windows: Type ping /t <the IP address you wrote down>"
• Watch the 1 second repeated pings.
• Lock the phone. Watch the pings start timing out after 20-30 seconds.
• Unlock the phone. What the pings restart.

Note that if an external signal is sent to the phone, the pings will resume for a few seconds. But an app on the phone that sends data will not.

Apple senior support advisor did run diagnostics on my phone last night, declared it fully OK and actually claimed wifi dropping is a feature not a bug.

So wifi drops intentionally to save power even though battery is full and device is on charger.

Wifi does turn on intentionally to perform iCloud backup etc during which you will receive notifications of course.

My experience was different before 10.3.3.

I posted a detailed report to the apple feedback site.

Probably a use case they missed: traveling abroad with no data roaming.

Dear kollamraku, I have seen your few comments sent to 'die hard apple fans' with a smile on my face first but then, after they go on and on, it really become tiring. Suggest you don't bother replying to them because obviously they don't have the problem we face with their device (at least not yet) and they have time to waste.

Meanwhile, did you try hard resetting your phone? I mean setting it up again as a new device (after doing a backup before of course)?

I have tried everything else but that to fix the issue....

Yes. It happens. It is supposed to happen. Circumstances and background processes that are actively using WiFi make keep the connection alive while they are active, but that doesn't change the fact that this behavior is by design.

Again, just FWIW, every one of the over 1 billion iPhones that have been sold in the past ten+ years disconnects from Wi-Fi when the phone locks, unless it is connected to power.