Can't connect to MySQL server on 'XX.XX.XX.XX' (13)

Hello dear experts!!!

Need help!

CentOS+MarisDB+PHP+Nginx

Have a test table in DB, that contain tow strings: ‘qwe’,‘asd’ ‘rty’,‘fgh’

Have a test script, that works if I lounch it from cmd:

$ php test.php <html><header></header><body>test page<br>qwe - asd <br> rty - fgh <br> </body></html>

So, MySQL+PHP works!!!

Have info.php file in the root dir of nginx, that works too (I see page in browser). So, Nginx+PHP works too!!!

But, when I request test.php by http, browser (and curl too) returns that: Can’t connect to MySQL server on ‘XX.XX.XX.XX’ (13)

I have installed LEMP twice with the same result by using this instruction: https://www.digitalocean.com/community/tutorials/how-to-install-linux-nginx-mysql-php-lemp-stack-on-centos-7

Several hours in internet didn’t provide any answers! Thanks for help!