When try to play matchmaking with a guest (split screen) it takes us back to the lobby after a few seconds. When I play solo it’s working. Help.
Not a fix but a workaround.
If you create a second Xbox live account it will work. It doesn’t need gold as long as the main account has a subscription. Then you can play.
I am having this same issue. Can’t play with my brother anymore, when I add guest it kicks back to the lobby after a few seconds. PLEASE HELP!!!
Whats your network configuration like?
Wired to the main host router?
What is the Mfr and model # of the main host router?
Whats the Mfr and model# of the ISP modem?
Be LAN cable connected to the main host router. Don’t use wireless if you can help it.
Try using a external LAN network swtich if your using two or more game consoles together on same network.
This is a confirmed workaround:
If you have the other players sign in as separate Xbox live accounts (instead of guests) it works fine. note it doesn’t have to be a paid account.
It seems too many people have this problem. 
Same issue - is anything being done about it?
Same problem for me today. This is unacceptable. This game has literally never run properly for more than a week it seems like.
Why the hell do we still have to use a work around?!
Check the playlists as well. You can’t do ranked with guests. Social playlists utilize different engines, so depending how the parameters work, one may be broken for guests on a certain engine. My first guess would be guest support for Halo CE seeing as it didn’t have Live functionality in the first place.
Go to customs, sign in a guest, and try loading a game into each Halo engine. If 1 fails, more than likely playlists that feature that engine won’t work as well as it may preload the engine data while searching.
Not sure how they configure stuff on this game but id start there. If the games load then it’s a prolly in the Lobby UI screwing it up.