Constant disconnection errors in co-op campaign

I’ve been having an issue where my brother and I keep having disconnection errors while playing co-op campaign. I’m on pc and he’s on xbox. We’re both from the uk. My gamertag is JAGMASK08. These errors can occur at any time in co-op but seem more common when in cut-scenes (that could just be a coincidence though). Sometimes these disconnects occur at the start of a mission, or more annoyingly, near the very end. We’ll both get kicked to the main menu without warning, and have a disconnection error saying “you have disconnected from the Halo wars 2 servers”, we will then be reconnected instantly. I know it isn’t an issue with our internet because we can play online fine through steam, other xbox games, and PSN. Any advice or support would be appreciated.