If you cannot connect or login (authenticate) to your server, you generally need to talk to your server administrator or hosting provider. We won’t be able to help you here, unless you have problems with WinSCP only and other clients works.
If you have problems specifically with WinSCP, make sure you use the same protocol in WinSCP and the other clients. WinSCP particularly defaults to secure SFTP protocol, while other file transfer clients typically default to FTP (or its secure variant FTPS, which is different to SFTP). If you still have problems, make sure you include log files both from WinSCP and the other client in your report.
If you cannot connect or login anyhow, check also the following articles, as they cover common mistakes and issues:
- Why is WinSCP not able to connect to a server, when other clients are?
- “Access denied” error message;
- “Server refused our key” error message;
- Other common error messages;
- Where do I get a username and password?
If you are connecting to your own cloud server, check also guides to connecting to various common cloud platforms (e.g. Amazon AWS, Google Compute Engine, Microsoft Azure, DigitalOcean, Backblaze, etc).