Hey I fixed it!!! If you have Sky, you need to disable the broadband shield. You just need access to the Halo Waypoint website to use the servers.
Just need to ask some questions though:
Do you use sky?
Do you live with your parents? (Because they may have set the shield up. I know my Mum did)
Can you access the Halo Waypoint website?
And can you access the Halo Channel app?
This all happened to me and I fixed it just by disabling the shield and entering the the halo waypoint URL into the exceptions. I hope that I have helped you enjoy the game more.
