This has happened to me almost 10 times today and it is very frustrating. When I’m playing warzone firefight (or at least that’s the only playlist its happened to me) I will suddenly get pulled out of my game and brought back to the home screen and I will have to restart my halo 5.
The game is very unstable on WiFi. if you can go wired and make sure your nat is open. That minimized my disconnects.