Connecting two phones that have only a Mobile Data Connection

Here I am going to describe how to receive glucose values and entered data from Juggluco running on one phone to Juggluco running on another phone, when both phones are only connected to the internet via a mobile data connection. If you want to connect two phones only over the home network, see: devices without NFC to connect via Bluetooth with the sensor.

In this description I use a Android device at home as a go between. You can also run Juggluco server on a computer.

The current setup is the following: Freestyle Libre Sensor->Realme phone<->Modem<->Tablet<->Modem<->Sony Phone

Forward a port from your Modem

The most difficult part is forwarding an extern port from the modem to the device acting as intermediary (the tablet). This will be different on different modems. I will describe here how to do it on my own modem, so that you have an idea for what to look in the user manual of your modem.

First you have to "create" an application, which in reality is nothing more than giving a particular port a name. I call this application port8795 and use port 8795.

After this you have to assign this application to a local device. We use the device I have called M5. Somewhere else in the modem interface, you can find that this device has IP and that is the home network IP of my tablet.

Go on your modem to where you can forward ports
Application Sharing
Press on New Application
New Application
Give a name
Specify port
Specify the port (8795)
Application Sharing
Press "Assign a game or application to a local network device"
Assign to M5
Select port8795 from Game or Application and the Device (here M5)
port8795 assigned to M5
port8795 assigned to M5
M5 information
Under the home network devices we see that M5 has the IP of my tablet,

External netwerk connections to port 8795 of the modem are now forwarded to port 8795 on

We have to find out what the external IP of the modem we have to connect to. You can find this in the modem interface or simple by visiting from a device on your home network.
Find my IP on

I found that my external IP was

On my tablet I now run Juggluco listening on port 8795, so that the smartphone can connect to it from the internet.

Realme phone: Connection to tablet

My Realme phone is connected to the sensor and should send data to my tablet. On this phone, I go to left middle menu->Mirror->"Add Connection", specify the external IP of my modem ( ). Don't set Test IP. To differentiate the different connections, we give it the label "realme". The connection on the phones should be set "Active only". We set what should be send to the tablet (Amounts, Scans and Stream) and specify a password for example "PassRealme". Specifying "Scans" when using Libre3 is a little bit strange, but you should also set that when you send Stream. You can leave you Amounts or set only send Amounts if you want. Press Save.

Sensor Phone
Add Connection to tablet on phone connected to sensor

Tablet: Connection to Realme phone

On the tablet we should specify the other side of the connection. "Passive only" because the phones are not accessible from the internet. Don't set Test IP. Set "Test Label" with the same label as on the Realme phone. set "Receive from" and the same password as on the other side of the connection (for example "PassRealme"). Press Save.

Tablet connection with Realme
Add Connection from Realme phone on tablet

If you press Sync on the Realme phone data from the Realme phone are send to the tablet.

Sony phone: Connection from tablet

Now, these data should be send to the other phone. On the Sony phone we again go to left middle menu->Mirror->"Add connection". Specify the external IP of the modem (For example:, unset Test IP. Set Test Label and use an arbitrary label "sony". Set "Active only", set "Receive from" and a password. Press Save.
Sony connection with tablet
Add Connection to tablet on Sony phone

Tablet: Connection to Sony phone

Go back to the tablet to specify the other side of this connection: Unset "Test IP", set "Test Label" with the label we also set at the other side of the connection, "sony". Set "Passive only", set what to send: "Amounts", "Scans" and "Stream". Set the same password as at the other side of the connection and Save.

Tablet connection to Sony
Add Connection to Sony phone on tablet

Sync on the Sony phone should start the reception of data from the tablet.