Game Shutting down ?

[Imp]

Being serious this is surely a technical issue at his end without knowing what he is running that’s affecting it finding the culprit will be hard. Uses same antivirus so switch it off, what other programs do both share, what runs at startup, what extras does the operating system have like bonjour frame network and are they up to date. Has he checked windows 10 and repaired it?
Good luck guessing what is affecting it could be some third party hook.