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Can Android devices connect to both WiFi LAN (not necessarily connected to the Internet) and mobile data networks at the same time? Or when it connects to one, does it have to disconnect from the other?

The device is Kyocera Hydro Icon with Android 4.4.2 if it's relevant.

Andrew T.
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Tim
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  • Related http://android.stackexchange.com/questions/29769/how-do-i-connect-to-a-wifi-ap-and-3g-network-simultaneously – Bharat G Oct 15 '15 at 02:05

4 Answers4

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Multipath TCP is a relatively new technology that allows a device to use multiple network connections for the same logical TCP connection. This is used for mobile phones to use WiFi and mobile data connections at the same time to reduce the time for retrieving data.

I'm not sure which Android phones currently support multipath TCP.

Without multipath TCP, a TCP connection must be either on WiFi or on the mobile data connection, but not both. It is up to the OS to decide how allocate these connections. I think the standard Android decision is to use WiFi if available (and perhaps with sufficient signal strength) to minimize cost under metered data plans.

mattm
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  • Long before mobile devices, people were writing desktop applications connecting to several network interfaces simultaneously. It was necessary to handle that on the application, not system, level.

    iOS supports that perfectly, as long as Linux, Windows, OS X.

    The developers in Android team broke Linux they used to build Android and introduced a flip-flop switch in the Kernel to switch between Wi-Fi and 3G. Very sad.

    Some developers were trying to remove that but it was very complicated. So, Android sucks.

     – Brian Cannard Sep 10 '17 at 18:03
  • This answer is valid, but in my opinion it does not match the question. The question was not if it is possible to use Wifi and cellular at the same time using the same TCP connection (e.g. use both connections for increasing network bandwidth or as fallback if one connection breaks). Thus Multipath TCP is not really relevant. – Robert Sep 15 '22 at 09:48
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I'm not sure about your phone, but the Samsung Galaxy S5 can do that. It offers a "Download Booster" ability which connects to a WiFi and mobile data network simultaneously while downloading a file.

Andrew T.
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Suuldat
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  • Thanks. Then how does the phone choose which network to download a file? – Tim Oct 15 '15 at 00:03
  • @Tim When selected both, the Android system will first try to connect to a WiFi-Network. If that didn't work, it will connect to mobile data automatically. Or did you mean the Download Booster function? – Suuldat Oct 15 '15 at 00:07
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On Android 6.0 Marshmallow or later, there is a developer option.

For previous versions, something like this should work. The methods numbers are Android version specific and these should work for Android 4.4 KitKat:

#!/system/bin/sh

radioM=20
mobileDataM=27
wlanIface=wlan0


turn on radio


service call phone $radioM i32 1


turn on mobile data


service call phone $mobiledataM


set mobile data as preferred network


service call connectivity $preferredNetworkM i32 0


wait for mobile data to connect


while [ -z "$(ip a | grep ccmni | grep inet)" ]; do sleep 1; done


reup wifi


ifconfig $wlanIface up


enable network bypassing android service


echo enable_network 0 | wpa_cli -p /data/misc/wifi/sockets/ -i $wlanIface
Andrew T.
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untore
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0

The Speedify app seems to work for this purpose, and for free if you don't use a lot of data: http://speedify.com/

I happen to own a Kyocera Hydro Icon, and just tested it on 4.4.2, and it seems to enable to my phone to connect to and stream audio from my WiFi hotspot solely when configured as a microSD card server (meaning, it's not connected to the Internet), and to still access data over my phone's 4G/3G.

mmortal03
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