The Halo:Reach servers are acting up. It says “The Halo:Reach server is unavailable at this time. Please try again later.” Also, sometimes peoples armor doesn’t load in correctly, or the games just lag out. Hopefully this gets fixed. 
Feel free to follow this topic for the time being until the issues is resolved:
https://www.halowaypoint.com/en-us/forums/cdecc00475c645b9a4d0a156fb542d59/topics/whats-up-with-reachs-servers/74c50894-d883-435d-8db7-174f1bee6876/posts?page=1