this post is for anyone having trouble with " contacting servers to get the latest matchmaking data. please wait." on december 17th me and my buddies were running into a possible bug? not sure but we couldn’t sign in even though other multiplayer games worked perfectly fine.
just sign out of xbox live and sign back in with your account this worked for me.

Yeah, I did the same thing when I had this issue.

Yeh but only noticed on Xbox so far, haven’t tried PC servers yet. Already posted servers issues on the support forum. Maybe servers are down for maintenance. Think it’s down to 343i’s servers since checked other games and they seemed fine.