Hello Kapil,
also it would be helpful to find out, where the connection breaks down. There are two different "network segments", where something can go wrong: a) the connection from HCP to your SCC (which goes through the Internet) and b) the connection from the SCC to the database (in the LAN).
1. Do you see any traces of the incoming request in the SCC? This would then show us, whether we need to investigate a) or b).
2. What protocol are you using to access the database? At the moment, the SCC does not support JDBC in the direction "HCP to on-premise", so I would assume you are using HTTPS. Is your database able to process HTTP requests on the given port? Otherwise this might also be a possible error cause: the DB is expecting JDBC/ODBC requests and does not know what to do with HTTP requests and does not send any response (and the HTTP client is waiting forever for the response, until network timeout...)
Best Regards, Ulrich