This issue commonly occurs due to networking problems. However, in some cases, it can happen because the user's IP address has been blocked by DarkStory's server due to previous security issues.
To fix this issue, you can follow these steps:
If you are not comfortable using the Command Prompt, restarting your computer may produce the same effects.
In some cases, users who have opened ports may not be able to connect to the server. You can try temporarily closing all the ports that you opened to fix this issue.