Ok, Here's the example screen shot (generic information). Syntax is important. You have to use a comma and the port number. Unfortunately, the password is in plain sight for anyone who knows where to find it. Fortunately, hardly anyone knows where to look,
and its buried pretty deep.
Excellent behavior: When you edit the query in the connection string field shown below, the workbook requires no changes to work on either a Mac or a Windows PC.

Thank you so much for the information and the screenshot. That's exactly how I thought it should be set up because it works perfectly on my Windows PC.
However when I set it up that way on the Mac, the password disappears out of the connection string when the Connection Properties window is closed. If I make any other changes to the connection string or command text, everything is saved. But that PWD=password
bit is always gone the next time it's opened. Therefore it's not saved.
The only difference between my file and your example is that I'm referencing the database by IP address.
I set the connection string up as:
DRIVER=SQL Server;SERVER=192.168.1.200,12345;UID=UserID;PWD=password;APP=Microsoft Office 2016;WSID=MachineID
And as soon as I click OK, and then go right back into properties, the connection string is missing the PWD bit:
DRIVER=SQL Server;SERVER=192.168.1.200,12345;UID=UserID;;APP=Microsoft Office 2016;WSID=MachineID
I thought maybe my file was corrupt so I created a brand new file and just set up a simple connection. Same issue. Any thoughts?