I can’t even load up the message of the day, just get the pinwheel loading screen of eternal patience. Seriously though what’s up with that? Did the servers go down or is something up?
I’m currently playing, so I don’t think the servers are down. They have seemed a little bugged to me for a few days though. My best advice would be to restart your game and try again.
There is a thread pinned at the top of the Halo 5 Support Forum (previous page) for discussing server related problems. You are likely to get more responses from there.
Most of the time any one-off problems with the servers can be solved by just waiting for them to clear up themselves, or by completing a cold reset of your Xbox One. To perform a cold reset, hold down the power button (Xbox logo on the front of your console) for 10 seconds. Additionally, I sometimes find resetting Alternate MAC Address in network settings on your console can make the game a lot more responsive.
Server Discussion Thread: