This kind of login issue is especially frustrating in a strategy game because even a short disconnect can affect events, resource management, and other time-sensitive actions.
From the discussion here, it looks like the problem is not always caused by the player’s own internet connection. Server load, maintenance, session timeouts, or temporary backend instability can also be responsible. I think the best first steps are to restart the game, check whether the connection is stable, try another network if possible, and wait a little if the problem started after an update or maintenance period.
It would also help if players shared the platform they are using, the approximate time the error appears, and whether the issue happens on Wi-Fi, mobile data, or both. That kind of information can make it easier to see whether the problem is local or affecting multiple players.
Hopefully the server-side stability continues to improve, because reliable login access is very important in a game where timing matters.