I have called Xbox live tech support to figure out the problem relating to the status, "Not Joinable", and they couldn't figure out the problem. So I figured it must be 343 Industries. They need to figure this problem and solve it, so all those like me with the status that says, "Not Joinable" and join and host our own game. So if anyone knows anything that can help or relate to this please comment to we can send a message to reach the tech team to solve our problem. Thanks! :-)