Dear all, it turned out that I could solve this via a NetworkManager dispatch script. FYI, it is a tad ugly still, but it works for now: https://gist.github.com/spaetz/be487e01e3958f72fa86ae66eef8c931 Just in case this turns up again. Sebastian P.S. If you find a solution to modify a user's gsettings in a less complex way, let me know :-)
