Able to Create SQL SmartObjects but Can't Execute Methods

I have a distributed environment in which I've created a SQL service instance which connects to an external SQL db (not on same server as K2 db).

The issue I'm having is that I am able to create SmartObjects based on the service instance (can see the table columns etc in smartobject tester), but when I attempt to execute the methods, I receive an error message from SQL server:

ERROR: Named Pipes Provider: Could Not open a connection to SQL Server [5]
OLE DB provider "SQLNCLI11" for linked server "dc-sql" returned message "login timeout expired"
OLE DB provider "SQLNCLI11" for linked server "dc-sql" returned message "A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL server Books Online."

A few more notes -
- Service instance is connecting in static mode with a dedicated SQL account. Have even tried giving that account sysadmin permission on target server
- No issues at all generating service instance, seeing artifacts from database, and generating smartobjects based on those artifacts (example: List method on sql view)
- SQL Login is perfectly fine, have tested remote connectivity via SSMS and am able to perform all necessary operations via SSMS
- Again, seeing errors only when trying to execute smartobjects

If anyone has any ideas they would be greatly appreciated.