Dear Agent,
In order to improve server stability and anti-plug-in system upgrade, the Mirror system is expected to undergo temporary maintenance on 1/21 11:15 (UTC/GMT: +8:00). Agents who are online will be forced to log off. please log off early to avoid loss! We will inform you later when the server is open. Sorry for any inconvenience caused to the simulation training! Temporary maintenance compensation will be issued after maintenance.
1/21 Temporary Server Maintenance bulletin
Source: Steam Community (opens in a new tab)