PHP script can't connect to MySQL when running from console and web server with the same settings?

Question

PHP

The connection string looks like this:

$mysqli = new mysqli('localhost:3306', "user", "pass", "db");

This works when run from the command line (php script.php) and the connection is normal. But it doesn't work when run through a web server ( localhost/script.php). At random, it turned out that if you remove the port, then it starts working on the web server, but it cannot work in the terminal at the same time:

$mysqli = new mysqli('localhost', "user", "pass", "db");

How to treat?

Answer 1

I'm a moron: these are different php being launched, which is why, apparently, the fakap.

Answer 2

Have you tried using localhost IP instead?

Answer 3

No, guys, that's not going to work. We don’t even bother to look at the documentation before writing such questions.
Are you used to what is indicated everywhere in the form of host: port? Nope.

$mysqli = new mysqli('localhost', "user", "pass", "db", 3306);

And localhosts have nothing to do with it. And don't ask why "it worked at least on console/webserver"