The official Halo Twitter recognized these issues and posted various statements in multiple tweets.
The full capacity of the Tweets read as followed:
We’re aware that some users are experiencing longer than normal Matchmaking search times. We are actively working on a fix for this issue. If after a few minutes you’re unable to find a match, exit Matchmaking and then begin searching again. – We’re aware of issues some have been having with matchmaking and we’re working around the clock, alongside the Xbox Live team, to address. – We’ve also deployed an update that has shown some improvement, and we work around the clock to optimize. This is our top priority. – The update deployed to matchmaking was done on the server side and does not require an extra download to your Xbox One.- Please refer to this Halo Support thread for continued updates on Matchmaking: http://bit.ly/11eRtP0
With my personal experience, I cannot say that I had to deal with the issues most others have had. Typically it would take no more than a minute to get a match started. Finding your match usually take 30+ seconds to start adding people, but they would pour in after the first one was found.
It’s good to see that 343i is quick to move in on these server issues to get the game running to it’s optimal performance.