I disconnected my ethernet cable and checked, story mode works offline battle works and missions works(IDK to what extent though since I am not that far in the game)
So online rank matches public events and the reward counter all require internet to play
I disconnected my ethernet and such as well to test things like that 2 and tried very small solutions on bypassing eac/disabling it that works on multiple other games. Sadly to no avail. But then again none of us are really coding anything.