Getaddrinfo fail inside the mqttClientService

then you need to embed your application into legato.cwe

After that combine the legato.cwe with modem and yocto and mcu image into one image by swicwe tool:

https://source.sierrawireless.com/resources/airprime/software/wp76xx/wp76xx-firmware-release-17-components/#sthash.fdXjPVgZ.dpbs

https://source.sierrawireless.com/resources/airprime/software/swicwe/

Of course, updating the official spk file and then just update you .update file will be easier for you