SQL Server with custom port

Using SQL Server with default port (1433) is work well. But when we use custom port, the .env or config field database.nls.port = 5000, its not given any effect, didn't work.
So, I tried to change connection syntax inside Connection.php core class CodeIgniter\Database\SQLSRV\Connection.

My questions:
1. Is this a bug ? because field database.nls.port (.env) or $default['port'] (config) doesn't work if we use custom port (especially for SQLSRV)
2. How do we override this Connection class. (Yes, I already read in the doc, create our own class, and register in autoload, but it didn't work).

Thank you.