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I've been looking for information on how the network created by an Android device's mobile hotspot is isolated (or not) from applications running on the device providing the hotspot.

The question is whether an application running on the device should be able to connect to/discover a TCP/IP service that is running on a device connected to its hotspot. Can anyone point me to documentation on how the hotspot network is or is not bridged the WiFi network that apps on the device use?

If I connect the Android device and the service running on the device to the same AP, I am able to discover the other device in an application running on the Android device.

If I connect the other device to the mobile hotspot provided by the Android device and then I attempt to discover a service running on the other device it fails. I assume this is by design, but can't find any documentation to clearly articulate what if any connectivity exists between the network the application can reach and the hotspot network.

I believe this scenario is better suited for WIFI direct but the other device does not support the protocol. If the WLAN network were bridged to the hotspot network it would work around this, but I don't believe it is just want to confirm before I rule this out.

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  • "If I connect the other device to the mobile hotspot provided by the Android device and then I attempt to discover a service running on the other device it fails." It's because the default gateway for apps is the internet facing network interface (probably your mobile data), not the hotspot facing interface. But you can easily get the desired results by modifying the routing table if your device is rooted. Start with ip rule and ip route. Apr 23 at 20:05

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