As the message says the i386 architecture isn't supported by this repository.
Please check the official-package-repositories.list repository list and see if the maui-xenial-backports-neon looks like this (copied from our original list that we ship with 2.1)
This makes sure that it only checks the amd64 (64bit) packages for that repo and gets rid of that warning about missing 32bit.
Please check the official-package-repositories.list repository list and see if the maui-xenial-backports-neon looks like this (copied from our original list that we ship with 2.1)
Code:
deb [arch=amd64] http://ds9-maui.s3-website.eu-central-1.amazonaws.com/maui-xenial-backports-neon xenial main
This makes sure that it only checks the amd64 (64bit) packages for that repo and gets rid of that warning about missing 32bit.