WiFi Disconnects when Lock Screen active

Whilst at Home, I've been wondering why with the iOS 11 release, I keep seeing messages saying that such and such an application doesn't have access to Mobile data, particularly when unlocking my device. Being at home, I'd have expected my iPhone to be constantly connected to my Home WiFi.

So, as a test, a ran a simple "ping" command from my PC, to the IP Address of my iPhone whilst it's attached to my Home Wireless router. Shortly after the iPhone screen goes dark, the Ping results start showing "Request timed out." followed by "Destination host unreachable". This continues until I press the Home button again.

So clearly, whilst the iPhone is in Lock-screen mode, the WiFi is disconnected. This didn't happen with Prior versions of iOS, so why now ?

As a consequence of this, iPhone system apps will now use the Carrier's 3/4G network for data (as you can't disable them) and any other application that you may have specifically permissioned for Mobile data access will be able to chew up your Carrier's data allowance. This explains why I've been seeing my data Mobile data usage creep up even though I haven't been away for WiFi.

Why is this now happening, it's surely a problem - particularly if you stream music overnight whilst you sleep.

iPhone 6s, iOS 11.1

Posted on May 9, 2018 12:06 AM

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17 replies

Birksv

Level 1

12 points

May 30, 2018 7:54 AM in response to IdrisSeabright

is there a way to turn that "feature" off?

svaardt Author

Level 1

133 points

May 13, 2018 7:56 PM in response to IdrisSeabright

Yes, I totally agree with you that data across "Mobile" #G Network isn't WiFi, but when WiFi is not available, Data is sourced via the Mobile Network if the "Mobile Data" function is switched on, and if that App has been permissioned for Mobile Data access. For the Myriad of System Services, it's always available - you cant switch them off.

So, what I am saying, is that a change has occurred in iOS 11 that makes these Messages relating to Mobile Data access more frequent, especially when unlocking the screen. Either this is because the WiFi is switched off whilst the screen is locked (proven), or once unlocked WiFi now take longer to reestablish and Apps therefore try Mobile data. Eitherways, the behaviour is different than before, otherwise I wouldn't have noticed it.

The Control center no longer works for me when the screen is locked, I have to unlock before "Swiping" upwards. I have an iPhone 6s - sourced in Japan - MKQU2J/A, perhaps there's a difference from other regional phones - say for example, those in the US or elsewhere ?

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WiFi Disconnects when Lock Screen active