Getaddrinfo fail inside the mqttClientService

[jyijyi]

here says it is fixed after legato 20.04:

MQTT Connection issues on WP7702 [AWS]

seems related to this one: I remember when I used the httpget sample with WP76 module, there is same problem of getting IP address inside application and this is fixed in later FW with legato 20.04. Currently you might try method to get IP addres inside program:

I assume you are using WP76 module, have you tried in FW17 of WP76 which is using legato 21.05?

(Bear in mind that once module upgraded to FW R17, you cannot go back to FW R16.x)