I had this problem today too. I had to change settings on my actual modem firewall to get my start button to "ungray". Someone suggested to turn it off which would work as well but I put it on lower setting than I normally do. I'm sure there is some port forwarding that could be done but I don't have that information. Lowering the security settings of my modem/router's firewall did the trick have been playing no problem ever since.