@cnx yes it's possible to configure servers that way and if indeed you have succeeded in this you will be the first (out of a half dozen) privacy-focused server admins who have set up a matrix instance who have succeeded in not having it phone home to vector.im. that's a problem with the software. all software can be modified to not do what you don't want it to do, that's not the point. all of the instances in the wild do this. also, my thread is about element the client, not your website.
@sneak, I’ve just tested in Firefox “private window” and from log in to starting a full session and there are only requests to halogen.chat and my homeserver shows up it the Network Monitor tab. I do not know what the admin did but certainly it’s possible to not rely on vector.im or matrix.org