I would appreciate it if someone could share a similar experience and/or solution to this problem.

I have this setup for the php dev environment

• Mac running apache2.4/php7.4/freetds1.4.26/php-pdo-dblib
• Parallel Desktop 20.2.2 running guest OS Windows 11 + dev db Sybase ASE 16
• Production db Sybase ASE 16 on a remote server
• test script db.php

<?php
try {
    $db=empty($argv[1])?$_REQUEST['db']:$argv[1];
    $dbh  = new PDO('dblib:host='.$db, 'sa', 'password');
    echo "Connected!";
} catch (PDOException $e) { 
    echo "Failed: " . $e->getMessage(); 
}

FreeTDS definition as

1. TESTDB (connect to guest on Parallel Desktop)
2. PRODDB (connect to live db on a remote server)

[TESTDB] # local parallel desktop
   host = 10.211.55.2
   port = 5000
   tds version = 5.0

[PRODDB] # remote production db
   host = 10.10.1.3
   port = 5000
   tds version = 5.0

Tests that I have done:

1. php-cli using TESTDB: php db.php TESTDB => Connected!
2. php-cli using PRODDB: php db.php PRODDB => Connected!
3. browser using TESTDB: HTTP://localhost/db.php?db=TESTDB => Failed: SQLSTATE[HY000] Unable to connect: Adaptive Server is unavailable or does not exist (TESTDB) (severity 9)
4. browser using PRODDB: HTTP://localhost/db.php?db=PRODDB => Connected!