For about an hour now I’ve been getting an error saying: “Error authorizing user with Halo 5: Guardians services. You will be unable to access online modes.”
Edit: It’s been almost 2 more hours now and I am additionally getting the Profile Sync error.
Edit: Restarting my console prompted a small update (approx. 35mb) for Halo 5 and I am now able to connect to the servers.