Hi rob,
Please get the Yocto Linux package and guide from “Linux Distro Source” section in below link:
https://source.sierrawireless.com/resources/airprime/software/wp77xx/wp77xx-firmware-latest-release-components/
(Please make sure your WP77xx is running same software version)
And you may find additional info from previous post in the forum, i.e.
Hope it helps.
Thx