Why does my data connection stop when I connect to wifi?

[Android Central Question]

This is a new problem following a forced upgrade to my Samsung Galazy S9 a week ago. When my phone is set to my wifi network, the connection to the Sprnt network stops. When I switch to mobile all works fine, but the connection to WiFi stops. Sprint insisted that was impossible. I finally changed to t-Mobile [after years of frustration on numerous issues and a better plan anyway]. During the in-store sign up I was told it didn't matter as my new plan had unlimited mobile data. As soon as I got home I turned my setting to my WiFi setting and immediately I lost connection to the T-Mobile connection. Turned WiFi off and the data connection came right back on. Called T-Mobile and they said "that's impossible". But it happens each time. So with WiFi on, no data; with WiFi off, data connection, but at some point this "unlimited data plan" will have limits of some kind. Is it me, my phone or what? PS-over 70 and low tech.

 

[mustang7757]

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https://forums.androidcentral.com/showthread.php?t=409154

 

[Mike Dee]

How do you know you're only on one?
Are you able to make calls when it's on WIFI?

 

[Rukbat]

Go to https://www.whatsmyip.org/ and see which one is connected to the internet under different conditions.

 

[B. Diddy]

Welcome to Android Central! I'm not quite clear on the problem -- are you saying that you want data to be coming over both wi-fi and mobile data at the same time? It's normal for the mobile data to pause while you're on wi-fi, since wi-fi is being used for data. Or are you saying that when you're on wi-fi, you can't even make a call?

 

[ManiacJoe]

It seems that the default setup of most phones is to turn off the cellular radio when the wifi is connected.

If you want both wifi and cellular radios to be active, you can turn on the "developer" options, then turn on the "cellular data always active" setting. (Your option naming may be different.)

 

[Mike Dee]

It seems that the default setup of most phones is to turn off the cellular radio when the wifi is connected.

If you want both wifi and cellular radios to be active, you can turn on the "developer" options, then turn on the "cellular data always active" setting. (Your option naming may be different.)

As far as I know when you turn on WIFI it just sends data to WIFI. You are still connected to the LTE network for calls.

 

[ManiacJoe]

Yes, the phone call system is always active. The cell data system by default gets turned off when the wifi data system is connected. When the cell data system remains on, there is no delay when swapping between the two systems nor any "temporarily not available" error when an app tries to directly connect to the cell data system like some voicemail apps like to do.

 

[methodman89]

Check the 2 settings I've circled

 

[Mike Dee]

Until the OP signs up we can't come up with a solid solution.