Unable to send UDP packets via NTN connectivity

RE: Unable to send UDP packets via NTN connectivity

Syed Maysum Abbas Zaidi — Wed, 10 Jun 2026 07:23:19 GMT

Hi,

Glad to know its fixed, I am closing this ticket and feel free to open a new ticket if anything else comes up. Thanks.

Best Regards,
Syed Maysum

RE: Unable to send UDP packets via NTN connectivity

barbiz — Tue, 09 Jun 2026 13:18:34 GMT

Hello!

the issue was on the carrier side (routing between APN and public internet) and it was solved.

Thanks for your help.

RE: Unable to send UDP packets via NTN connectivity

Syed Maysum Abbas Zaidi — Mon, 18 May 2026 11:32:58 GMT

Hi,

Thanks for testing with flag 512. It means the modem believes it transmitted the packet over NTN, but does not prove it traversed the operator core or reached your server, this do suggests that there is an issue on operator side however can you please run one more check, which can tell if the send is acknowledged:

AT#XSENDTO=0,0,8192,"18.199.178.22",9999,"test"

Then wait for the #XSENDNTF. If status = -1, the modem itself reports a failure. If status = 0 but nothing arrives at the server, the issue is downstream (operator path or firewall).

Moreover please share the Modem traces with AT#XTRACE command, so we can debug it further.

Best Regards,
Syed Maysum

RE: Unable to send UDP packets via NTN connectivity

Geolink_olivier — Wed, 13 May 2026 02:06:16 GMT

Are you sure you are using the proper APN? I have been using ntn with monogoto and data.mono is what you should use, not go.mono

RE: Unable to send UDP packets via NTN connectivity

barbiz — Tue, 12 May 2026 23:12:49 GMT

Hello,

thanks.

I did that, and the packet seems to be sent.

> AT#XSENDTO=0,0,512,"18.199.178.22",9999,"test"

#XSENDTO: 0,0,4

OK

However, I get nothing at the other side and no traffic in the Monogoto platform...

I am using:

serial_modem_v1.0.1_nrf9151dk_normal
mfw_nrf9151-ntn_1.0.0

Marco

RE: Unable to send UDP packets via NTN connectivity

Syed Maysum Abbas Zaidi — Mon, 11 May 2026 14:02:18 GMT

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