This blogpost explains how to connect .NET Core Console application to SQL server database and read table data. You will not be using the Entity framework for this.

Windows 7 includes an ODBC manager that lets you connect from your desktop to a SQL server. You create a data source name (DSN) to save database setup information, so you can open a connection to ...

This could be because the pre-login handshake failed or the server was unable to respond back in time. The duration spent while attempting to connect to this server was - [Pre-Login] ...