I can not connect to my server. "Unknown host"

I can’t access my server due to an "unknown host" error. I watched various discussions and questions, tried to enter from a regular IP, from Dyn-IP... I cleared my DNS, nothing helps. And at the same time, I can’t access not only my own but also any other aternos server. The strangest thing in this situation is that when I try to log into a turned off server, I even have “Logging In” and can read that the server is offline (See the screenshots below). But when I try to access the same server, only when it is on, I have this "Unknown host" (See the screenshots below too). Help me plz