Unable to connect to MS SQL Server

I use SSMS and would like to try HeidiSQL as an alternative. I am unable to connect to any of the databases I use regularly - and successfully - via SSMS from the same PC.

I am trying to use named pipes with windows authentication, but I have tried many other options.

I get:

"SQL Error (17): [DBNETLIB][ConnectionOpen (Connection().]SQL Server does not exist or access denied"

Any ideas?

You need to activate one of the connection protocols in your MS SQL configuration. For example, I had to enable TCP/IP connections before I could connect via HeidiSQL.