As roaming is more or less transparent for the device as well as backend-end server, this recommendation formulated here https://forum.iotcreators.com/topic/594/data-packet-size still applies.

@rxtx

AT+COPS=1,2,"20416"
2022-02-17T10:57:35.077Z DEBUG modem << OK
2022-02-17T10:57:38.329Z DEBUG modem >> AT+CFUN=1
2022-02-17T10:57:38.378Z DEBUG modem << OK

You turn on the radio after you perform the manual attach. This looks strange for me. Not sure whether the manual attach works in this case. Please turn on the radio (at+cfun=1) before you perform the manual attach. usually you can can choose the RAT type while doing the manual attach. That would be:

AT+COPS=1,2,"20416",7

7 for LTE-M on your module. Try this pls. not sure whether that works on your module.

BR,
Kolja

I can confirm the issue. I can reproduce it. The problem occurs not due to LTE-M but due to this specific APN (m2m.public.nl). @Uta will take care of this

I can confirm the issue. I can reproduce it. The problem occurs not due to LTE-M but due to this specific APN (m2m.public.nl). @Uta will take care of this

I will look into that. In the meantime:
Have you already tested IPv4 ?

@aliza-izaton As mentioned earlier, I strongly recommend using a python-based solution.

@rxtx Perfect!

@rxtx

AT+COPS=1,2,"20416"
2022-02-17T10:57:35.077Z DEBUG modem << OK
2022-02-17T10:57:38.329Z DEBUG modem >> AT+CFUN=1
2022-02-17T10:57:38.378Z DEBUG modem << OK

You turn on the radio after you perform the manual attach. This looks strange for me. Not sure whether the manual attach works in this case. Please turn on the radio (at+cfun=1) before you perform the manual attach. usually you can can choose the RAT type while doing the manual attach. That would be:

AT+COPS=1,2,"20416",7

7 for LTE-M on your module. Try this pls. not sure whether that works on your module.

BR,
Kolja

@Adriaan Can you share the pcap file with us?

You think that he button does not close the TCP socket correctly (meaning without sending FIN)?

@magnatron would be great of you could share your experience/problem/solution with us.

@magnatron Have you done a network search already?

@Adriaan Could you share a screenshot of your Wireshark Log with us?