Commented Unassigned: DB server with custom port causing error [20423]

I'm having an issue where the script will not continue, apparently because of custom SQL port. My customer is using a custom SQL port, 18000, for their SQL instance. When I add the DB server name to the script, it cannot connect to the database. Since it is a local DB, I remove the name. installation works but when it gets to the step for configuring the farm, I get the error:

- Attempting to join farm on "SP_Config"...
- Script halted!

System.Management.Automation.ParameterBindingValidationException: Cannot validate argument on
parameter 'DatabaseServer'. The argument is null or empty. Supply an argument that is not null
or empty and then try the command again. --->

So far, I can't find any combination that works. if I populate the database server, it doesn't connect and continue. If I leave it blank, the script runs until it tries to configure the farm.

Version 3.95 running on Windows Server 2012
Comments: ** Comment from web user: brianlala **

FYI I just did a client install where they were using a custom port, no issues. Would have to see your XML to know exactly why it was failing in your case.

Brian