I've tried resetting my router and modem, but I get no luck. My Xbox connects to my network and the internet without an issue, but it won't get me onto Xbox LIVE. I tried to use this: http://support.xbox.com/en-CA/xbox-live/errors/error-code-80151909 which turned out to be a bad idea, because I deleted my profile (not with the items or anything), and when I went to download it, my Xbox won't connect to the internet anyway, so I can't download it. Phew, long sentence.
All that's suggested is that I unplug my router/modem (done that three times now) or do manual port forwarding (I already had done that). I tried to restore to factory settings for the network (or whatever the option is called), and that did nothing as well. So, now I'm here. I've been trying to connect for over an hour now and nothing's changed.
I should also add that sometimes the 80151909 code is 80151901 instead.