My launcher also takes a while to really start the upgrade after I click the button, but I just wait a while and it does start after a few minutes (5 or so I think). So, maybe just wait longer.
Also, I'm on wireless and it works fine for me. Got something like a 3.7 Mbps connection, which is pretty slow. On downloads I usually get a little over a gig an hour. This update only took a little over an hour which is awesome. Love the way Elite Dangerous updates: seems like it should take a lot longer than it actually does. I'm guessing that has something to do with the whole "syncing files" thing.