How to connect to SQL Server: you must specify the port not the instance

I am trying to use Knime coming from Alteryx, and I have already wasted more than an hour trying to connect to a MS SQL Server, with no luck!

I need to import a CSV file into SQL. I have set up a file reader node, run it and verified that it reads the CSV correctly.

Then I connect a DB Writer node, but I cannot configure it because “the dialaog cannot be opened for the following reason: database connection is not available”. But how am I supposed to set up the database connection if I cannot configure the node???

Then I tried to configure a “Microsoft SQL Server Connector”. I specified the hsotname, the port, the database name, and “native authentication”.

If I then run the node, I get “Execute failed: Unknown server host name 'MYSERVER\SQLEXPRESS”

What am I doing wrong? Could it be that some drivers are not installed? How do I verify that?

By the way, I can connect to that server using DataGrip and SQL Alchemy (with Python) just fine.

Thanks!