Firebird Connection Problem

Hello.
My name is Frans.
And i have some issue about the connection Firebird Server.
In my server, i have installed Firebird Server with command line (Windows) and it takes successfully to run the apps.
When the problem is curious, that the client can't login with the first time. It show the host is unreachable.
But when i close the error message, then i click the login again. It was success.
I don't know what is the problem.
The error message is INET/inet_error: read errno = 10054 in firebird.txt

Please help.

Thank you,
Frans Wiradinata