Unable to send UDP packets via NTN connectivity

[barbiz]

Hello,

I am evalating the nRF9151-SMA-DK with a Monogoto SIM card that uses Skylo NTN connectivity.

I am able to reach the internet, since DNS resolution works:

Ready
> AT%XSYSTEMMODE=0,0,0,0,1

OK
> AT%XBANDLOCK=2,,"23,255,256"

OK
> AT%LOCATION=2,"45.40946744518183","11.910658449997351","0",0,0

OK
> AT+CGDCONT=0,"IP","go.mono"

OK
> AT+CEREG=5

OK
> AT+CNEC=24

OK
> AT+CSCON=3

OK
> AT%MDMEV=2

OK
> AT+CFUN=1

OK

%MDMEV: SEARCH STATUS 1

+CEREG: 2,"3AA3","00110383",14

%MDMEV: PRACH CE-LEVEL 0

+CSCON: 1,7,4

+CEREG: 5,"3AA3","00110383",14,,,"11100000","00111000"

%MDMEV: SEARCH STATUS 2

+CSCON: 0,7,4
> AT#XGETADDRINFO="google.com"

#XGETADDRINFO: "142.251.14.138"

OK

%MDMEV: PRACH CE-LEVEL 0

+CSCON: 1,7,4

Then I have set an UDP server, public on the internet, at address <server_ip>

I tested the reachaiblity of the server from public network with my pc as a client using a python script to send UDP packets.

However, when sending UDP packets with the nRF9151, nothing gets to the server.

> AT#XSOCKET=1,2,0

#XSOCKET: 0,2,17

OK

> AT#XSENDTO=0,0,0,"<server_ip>",9999,"test"

#XSENDTO: 0,0,4

OK

The provider confirms the SIM card is configured correctly, however I am unable to continue testing.

Can you help me?

[Syed Maysum Abbas Zaidi]

Hi,

Your AT#XSENDTO response looks correct as it confirms 4 bytes were pushed to the modem buffer but to verify actual network delivery you may change your send command to use blocking mode, which waits until the data is actually pushed to the network:

AT#XSENDTO=0,0,512,"<server_ip>",9999,"test"

Also please make sure you are using NTN modem firmware (mfw_nrf9151-ntn_1.0.0). Thanks

Best Regards,
Syed Maysum