Waking the device: cellular vs wifi

[gordol]

I've had my iPhone 5 for about three weeks now, and I've been noticing that when I wake the device from sleep (ie, turn on the screen) most of the time it shows 3G instead of WiFi. This is happening where it is connected to a remembered WiFi location that does not need to go through a proxy/login screen. Such as my or my brother's homes. My iPad2 does not do this. Both devices are on iOS 6.1.

Before I keep an Apple Genius Bar appointment tomorrow to swap the iPhone out for a new one (it's a two hour round trip) I wanted to see if anyone else has noticed this problem. If it's endemic, then the new one will do the same thing and it would have been a wasted trip.

What's been done so far to troubleshoot:

Full device reboot
Reset the network settings

Testing to make sure it's really happening and not a display glitch of some kind:

The device is set to automatically download newly purchased apps, with the "on cellular" option off, so in theory it should only do that when on WiFi, so yesterday with the device sleeping, via iTunes on my PC I "purchased" a free app that I was going to get anyway. When I woke the device, it was installed.

OTOH, I just installed the Remote app and set it to control my iTunes. With Remote active, I let the phone go to sleep. A few minutes later I attempted to change the playback volume and when I woke the iPhone, Remote was telling me that it had no network connection to iTunes. A split second later, it found the connection, then lost it, then connected solidly.

 

[jclisenby]

I've had my iPhone 5 for about three weeks now, and I've been noticing that when I wake the device from sleep (ie, turn on the screen) most of the time it shows 3G instead of WiFi. This is happening where it is connected to a remembered WiFi location that does not need to go through a proxy/login screen. Such as my or my brother's homes. My iPad2 does not do this. Both devices are on iOS 6.1.

Before I keep an Apple Genius Bar appointment tomorrow to swap the iPhone out for a new one (it's a two hour round trip) I wanted to see if anyone else has noticed this problem. If it's endemic, then the new one will do the same thing and it would have been a wasted trip.

What's been done so far to troubleshoot:

Full device reboot
Reset the network settings

Testing to make sure it's really happening and not a display glitch of some kind:

The device is set to automatically download newly purchased apps, with the "on cellular" option off, so in theory it should only do that when on WiFi, so yesterday with the device sleeping, via iTunes on my PC I "purchased" a free app that I was going to get anyway. When I woke the device, it was installed.

OTOH, I just installed the Remote app and set it to control my iTunes. With Remote active, I let the phone go to sleep. A few minutes later I attempted to change the playback volume and when I woke the iPhone, Remote was telling me that it had no network connection to iTunes. A split second later, it found the connection, then lost it, then connected solidly.

The way the iPhone is designed allows the WiFi connection to "sleep" when the device is locked. It defaults to cellular for notifications, calls, and messages when the device is locked in standby mode.

So when you unlock the phone, it immediately connects back to WiFi. There's nothing wrong with your iPhone. They all do this way locked.

I know you were hoping for a different answer, but this is just the way the product was designed.


Tappin and Talkin from my iPhone 5

 

[kch50428]

There's nothing wrong with your phone. It's supposed to work that way... when asleep - the wifi sleeps to conserve battery... unless plugged in, in which case, wifi stays fully awake for things like wifi sync, and iCloud back-ups.

 

[gordol]

There's nothing wrong with your phone. It's supposed to work that way... when asleep - the wifi sleeps to conserve battery... unless plugged in, in which case, wifi stays fully awake for things like wifi sync, and iCloud back-ups.

If that is the case, then why didn't the Apple Care rep tell me that when I called? Then again, he asked me to update to 6.1.1 after I told him I'm using an iPhone 5...

 

[John Yester]

WiFi has always been automatically turned off here when the phone is locked (in iOS 5 etc... ) after a few minutes ... that's an iOS feature, as Apple considers that the phone in standby will use less battery on cellular data than on WiFi. This said, as soon as you turn the phone back on (light up the lock screen), you'll notice that the phone switches back very quickly from 3G to WiFi, and this, already before you unlock.


This built-in behavior won't change in "do not disturb" mode on iOS6.

 

[kch50428]

If that is the case, then why didn't the Apple Care rep tell me that when I called?

Probably not deep enough into the script...

 

[gordol]

WiFi has always been automatically turned off here when the phone is locked (in iOS 5 etc... ) after a few minutes ... that's an iOS feature, as Apple considers that the phone in standby will use less battery on cellular data than on WiFi. This said, as soon as you turn the phone back on (light up the lock screen), you'll notice that the phone switches back very quickly from 3G to WiFi, and this, already before you unlock.

Not arguing, but some related questions for clarification:

When I was still using a Droid, I had heard that WiFi uses less power than cellular. Is that not true at all, or not true for iDevices? Before it became unreliable, the Droid X did not drop WiFi just because the device was idle.

When I wake the device, it usually does not show WiFi until up to a second and a half (or so) later. I can wake and unlock faster than that.

It's not the battery life I'm worried about here, it's the cellular data usage. When I upgraded to the iPhone, I lost my unlimited data on Verizon and I would really hate to have my background idle data usage be what pushes me over my quota.

If I'm actively downloading something on WiFi and the iPhone auto-locks due to my configured idle time, will it keep the download on WiFi, or will it drop to cellular?

 

[John Yester]

Actually I think all that means is, is an indication of which cell network you are on. The WiFi is always on, but occupies the spot on the screen. Call it a courtesy glance at the cell connection. It does not mean the WiFi was off. The WiFi is always on, even when sleeping. Has to be, to pick up e-mail either push or a fetch interval. All that stuff continues to run during sleep.

Testing settings not long ago on my Router. The iPhone with an IP of 192.168.1.8 shows connected.

Now device is locked/stand by Refresh router list and device not connected.

I sent iMessages and email. Once the device received them the device showed up on the router list.

So IMO don't think of WiFi as OFF. It's on all the time.... Just not "Connected" until something hits and it's received via WiFi vs your cell connection

 

[gordol]

Actually I think all that means is, is an indication of which cell network you are on. The WiFi is always on, but occupies the spot on the screen. Call it a courtesy glance at the cell connection. It does not mean the WiFi was off. The WiFi is always on, even when sleeping. Has to be, to pick up e-mail either push or a fetch interval. All that stuff continues to run during sleep.

All of which works just as well on cellular.

Testing settings not long ago on my Router. The iPhone with an IP of 192.168.1.8 shows connected.
Now device is locked/stand by Refresh router list and device not connected.

So it does disconnect when asleep, and it's not just mine. A device swap will not work.

 

[John Yester]

To the best of my knowledge no a device exchange will not accomplish anything.



It's the OS.

 

[kch50428]

So it does disconnect when asleep, and it's not just mine. A device swap will not work.

The display gives an appearance of disconnect - it's more like a "hot standby" that goes full-on on demand. It's not a bug or defect - it's a feature.

 

[John Yester]

Also a good point is if your device is connected to external power, it should keep the wifi on when it goes into sleep mode. If you have the external power disconnected, then it will turn the wifi radio off when it goes to sleep to conserve battery.

Also on an iPad it will never drop connection, being a WiFi only version. but I wonder if someone with a Cell/WiFi version can confirm.

The WiFi iPad will never drop connect or IP on my router, as I have tested...

 

[Massie]

Also a good point is if your device is connected to external power, it should keep the wifi on when it goes into sleep mode. If you have the external power disconnected, then it will turn the wifi radio off when it goes to sleep to conserve battery.

Also on an iPad it will never drop connection, being a WiFi only version. but I wonder if someone with a Cell/WiFi version can confirm.

The WiFi iPad will never drop connect or IP on my router, as I have tested...

True about the iPad and I believe iPods as well. This is all by design and has been this way for quite a while. It comes up a lot on the forum:

http://forums.imore.com/iphone-4s/229420-switching-3g-when-screen-locks.html
http://forums.imore.com/iphone-5/243339-wifi-sleep-mode.html
http://forums.imore.com/iphone-4/207087-3g-wifi-lock-screen-story-8-a.html
http://forums.imore.com/iphone-4/218496-wifi-shut-off.html

Nothing to worry about, I think.

 

[p3t3rPan]

It's not the battery life I'm worried about here, it's the cellular data usage. When I upgraded to the iPhone, I lost my unlimited data on Verizon and I would really hate to have my background idle data usage be what pushes me over my quota.

If I'm actively downloading something on WiFi and the iPhone auto-locks due to my configured idle time, will it keep the download on WiFi, or will it drop to cellular?

If you have good wi fi just turn cellular data off. I get by with only 50 mb of data allowance a month this way. That's mb not gb.



Sent from my iPhone 4s using Tapatalk

 

[gordol]

Ok, I've cancelled my Genius Bar appointment.

 

[EauRouge]

gordol, as said before, it is the way its supposed to be. But Im with you- I dont like it. All my others devices hold wifi when in standby and from experience that helps reduce the battery drain. I dont know why its different with iphone, but it is what it is

 

[plt3121MarineAlways]

It could be because iPhones have a good if not great battery life so the need isn't there like it is with other devices. Just a thought..

 

[gordol]

If you have good wi fi just turn cellular data off. I get by with only 50 mb of data allowance a month this way. That's mb not gb.

Three weeks in, I'm at around 60MB used... A far cry from my allotted 2GB to be sure, but my usage will likely go up after I start working again and I'm away from my home WiFi.