Since yesterday I haven’t been able to play any multiplayer matches, I wait a bit, and sometimes it’s a long time, the blue bar with all of the info appears (joining match, number of players, etc), then the screen goes black with the 3 loading dots on the top left corner, I wait a couple of seconds, mabey a minute and it takes me back to the main menu. It only happens with multiplayer and sometimes it says that there may not be enough players in this mode so I should try an other, or that the search has timed out/I’m offline when I’m actually online. It’s rather annoying because I’ve only played 2 or 3 games so far. This all begun after I exited the game last night so I could go and have dinner. I submitted a ticket for this problem yesterday and they said they received it, but apart from that I haven’t received any other response. I read on twitter that someone was having a similar problem to mine, and someone else told them that it stops happening after a couple of trees but I have attempted to join lots of games and it’s failed every single time. 
If you are encountering issues during the flight, please refer to the known issues list on https://aka.ms/HaloSupportInsider and submit tickets for issues not present.
For general feedback that is not a bug or issue, feel free to use the pinned feedback threads at the top of the Halo Infinite forums
https://www.halowaypoint.com/en-us/forums/29568daf8cd14083bd1b70a810bf3581/topics