Halo MMC cant sign in.

I'm Samy an independent advisor. Welcome to the Xbox community. How are you?

These steps can help you, give it a try.
Check for updates on Windows Update, update everything including optional/additional updates.
1. Logout from Xbox app and Microsoft Store app
2. Look for the Xbox app and Microsoft Store app in the Windows menu, right-click, click app settings and then click terminate, restore and reset. Do this for the game too.
3. Clear the store cache type ''wsreset'' in the Windows bar, run as admin, and wait for the screen to close and open the store automatically.
4. Open the Microsoft Store app, click on the 3 dots in the upper right corner>downloads updates>get updates and update everything.
5. Press the Windows Button then type Services.
Right-click over the Services App from the list of results.
Then select Run as Administrator
Scroll to the bottom and find the following services:
IP Helper
Xbox Live Auth Manager,
Xbox Live Game Save,
Xbox Live Networking Service,
Gaming Services.
Do this with each of the services listed above.
Right-click over the service and select Properties.
Find the Startup type section and make sure it’s set to Automatic.
If the service isn’t started, click Start to start the services.

Click Apply and OK to save changes.

6. Restart your PC, log in to both apps and see if that solves the problem.

I'll be scratching Halo 5 off my list until Halo MMC gets it's multiplayer fixed.

Just realised this game releases a week before Halo MMC. No point buying COD. Everyone will be online with Halo.

Halo MMC

Outer Worlds

Forza Horizon 4

Gears of war 5

Friday the 13th, Forza, Real Royale, Halo MMC. Those would be my recommendations.

#XboxAmbassadors