Unable to Connect Remote Desktop to the EC2 Instance of Windows Server in AWS

I created a Windows Server (free version of Micro2) in an EC2 instance of Amazon WebService and used it with a remote desktop connection, but when I tried to RDP from a different client PC than my previous PC,
You will not be able to connect.
Once this phenomenon occurred and when I tried to connect again with a PC that I had been able to connect to, the same phenomenon appeared. You will no longer be able to connect.

Could you tell me the cause and countermeasures?

The above dialog appears and does not proceed with entering login information.

Thank you for your cooperation.