Network/NAT/firewall/connectivity issues
While Company of Heroes 2 is available on Windows, macOS, and Linux, these versions are not compatible for multiplayer.
If you play modded COH2, the "Match No Longer Exists" error is twice as likely. Mods like Blitzkrieg and Wikinger add thousands of custom assets. If any player in the lobby has a different mod version (even a 0.01 disparity), the server aborts.
The error message in Company of Heroes 2