MQTT_Simple: getaddrinfo failed -2

If you're using NB-IoT, you should configure the modem with "at_cmd_write("AT%XEPCO=0", NULL, 0, NULL);".

This disables the "extended protocol configuration options" and falls back to legacy mode. Then it should work for Telenet NB-IoT (and same for Proximus NB-IoT btw).

https://infocenter.nordicsemi.com/index.jsp?topic=%2Fref_at_commands%2FREF%2Fat_commands%2Fpacket_domain%2Fxepco.html

This is solving the issue.

But it has to be executed before establishing the NB-IOT connection (not just before the DNS call)

How I added it to the main:

#endif /* defined(CONFIG_MQTT_LIB_TLS) */
err = at_cmd_write("AT%XEPCO=0", NULL, 0, NULL);
LOG_INF("AT%%XEPCO=0 result: %d",err);

	do {
		err = modem_configure();