System Security is of paramount importance, and Agency Software is no exception. This is especially true when the core back office product also connects to the internet for direct customer and employee access.  In the early days of MS SQL7 the application could connect by default. Indeed the connection was broadcast or advertised across a network for all to see. With Windows Server 2008 by default all is turned off and even if you are logged in with Admin privileges, these may not be inherited in a consistent fashion by an application you run. Resolving connection issues is a trial which the following article may help you to win:

https://blogs.msdn.com/sql_protocols/archive/2008/04/30/steps-to-troubleshoot-connectivity-issues.aspx