Lost Wifi in Mobile Phone?

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  • Updated 8 months ago
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Hi all,
My company is using Access Point 7502E. I connect my mobile phone to WIFI. But when i lock screen of mobile phone, Connect is lost (I can't ping to IP of mobile phone--> Internet is drop). then, when I unlock screen, My mobile phone is automatic connect to network. How to fix the problem?
Help me!
Thanks 
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Long Tran

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Posted 8 months ago

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Sam, Employee

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Mobile devices will go into power save mode when they are not being used to prolong battery life, this is normal behaviour. I would advise reading up on DTIM and TIM functionality to help understand why the devices do this. 

Hope this helps,

- Sam 
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Long Tran

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No. I turn off Power Save in mobile phone  but no fix problem.
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Ondrej Lepa, Employee

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Hi Long,

what phone are we talking about?
Anyway - lot of phones are just turning off the wireless when screen locked.

Regards,
Ondrej
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Darrel Rhodes, Employee

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Sam is correct.  You may be able to disable some of the device's power save features (such as screen dimming, etc.) but the Wi-Fi element of the device will still sleep if the device is in a state where connectivity is not required, such as when the screen is locked, and therefore user interaction isn't possible. 

This is common and standard on all mobile phones.  I just checked my iPhone6s which was active less than a minute ago but the screen had turned off and was locked and when I hit the home button Wi-Fi was disconnected.

Why is it you need connectivity even when the the screen is locked? Which mobile OS are you using?

Thanks,
Darrel.
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Long Tran

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I use Iphone 6, IOS 10.3.x. I need connect wifi when the screen islocked because I need to be notified when mail (gmail, outlook, skype,...) arrives. And when i use other wifi, no problem.
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Sam, Employee

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The client should wake to hear a beacon from the AP based on the TBTT (Target Beacon Transmission Time). If there is any buffered unicast traffic at the AP for the client, the AP will put the clients AID (Association Identifier) in the TIM (Traffic indication Map). The client should then check this beacon for its AID and will send a PS-Poll frame to the AP. When the AP gets this frame it will send the buffered traffic. 

You can see all of the above in a packet capture. 

How are you testing this? Are you sending emails and Skype's while the screen is locked? Also how have you turned off power save mode on the iPhone? 

-Sam 
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Long Tran

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Hi Sam,
I turn off Power Save in Setting --> Battery --> Low Power  Mode --> Chose Turn off.

Other hand,  When I connect in other wifi network, that problem does not appear
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Sam, Employee

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That doesn't disable the power saving functionality for the device: 

Low Power Mode reduces or affects these features:

  • Email fetch
  • "Hey Siri"
  • Background app refresh
  • Automatic downloads
  • Some visual effects
  • Auto-Lock (defaults to 30 seconds)
I'd advise you open up a case with GTAC so that they can review your wireless configuration. 

Best regards,
Sam 
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Darrel Rhodes, Employee

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There are some useful (anecodtal) pointers here that might help.
https://apple.stackexchange.com/questions/218354/how-to-prevent-iphone-from-dropping-wifi-connection...
 Interestingly (and I'm running WiNG 7622 APs) my iPhone 5C stays connected in sleep but my iPhone 6S reverts to cellular when asleep.  So looks to be a phone issue, if anything.

Thanks,
Darrel.