PHP on OMV 4.0 is not running at all

Hi
I'm OMV user since version 0.2 and very happy with functionality of this software.
I recently run into problem as had to reinstall OMV box due to disc failure.
Currently i have installed version 4.0 and so far so good except problems with php module.
My websites i was hosted previously seems to work, however without php functionallity.
How i can check if php is working and eventually allows websites to use php code.
For nginx and php pool configuration i have used below tutorial (8:20min):

Please help

Unfortunatelly dont working means even simplest test .php files on webfolders outputting 502-Bad Gateway error
When I'm tested using command :service php7.0-fpm status
got:
Active: active (running) since Tue 2019-05-28 13:44:28 CEST; 24h ago

There a list of php modules installed:

ii php 1:7.0+49 all server-side, HTML-embedded scripting language (default)
ii php-bcmath 1:7.0+49 all Bcmath module for PHP [default]
ii php-cgi 1:7.0+49 all server-side, HTML-embedded scripting language (CGI binary) (default)
ii php-common 1:49 all Common files for PHP packages
ii php-fpm 1:7.0+49 all server-side, HTML-embedded scripting language (FPM-CGI binary) (default)
ii php-mbstring 1:7.0+49 all MBSTRING module for PHP [default]
ii php-pam 1.0.3-1 amd64 pam module for PHP 7
ii php-symfony-class-loader 2.8.7+dfsg-1.3+deb9u2 all load PHP classes automatically
ii php-symfony-polyfill-apcu 1.2.0-1 all Symfony polyfill backporting apcu_* functions to lower PHP versions
ii php-xml 1:7.0+49 all DOM, SimpleXML, WDDX, XML, and XSL module for PHP [default]
ii php7.0 7.0.33-0+deb9u3 all server-side, HTML-embedded scripting language (metapackage)
ii php7.0-bcmath 7.0.33-0+deb9u3 amd64 Bcmath module for PHP
ii php7.0-cgi 7.0.33-0+deb9u3 amd64 server-side, HTML-embedded scripting language (CGI binary)
ii php7.0-cli 7.0.33-0+deb9u3 amd64 command-line interpreter for the PHP scripting language
ii php7.0-common 7.0.33-0+deb9u3 amd64 documentation, examples and common module for PHP
ii php7.0-fpm 7.0.33-0+deb9u3 amd64 server-side, HTML-embedded scripting language (FPM-CGI binary)
ii php7.0-json 7.0.33-0+deb9u3 amd64 JSON module for PHP
ii php7.0-mbstring 7.0.33-0+deb9u3 amd64 MBSTRING module for PHP
ii php7.0-mysql 7.0.33-0+deb9u3 amd64 MySQL module for PHP
ii php7.0-opcache 7.0.33-0+deb9u3 amd64 Zend OpCache module for PHP
ii php7.0-pgsql 7.0.33-0+deb9u3 amd64 PostgreSQL module for PHP
ii php7.0-readline 7.0.33-0+deb9u3 amd64 readline module for PHP
ii php7.0-sqlite3 7.0.33-0+deb9u3 amd64 SQLite3 module for PHP
ii php7.0-xml 7.0.33-0+deb9u3 amd64 DOM, SimpleXML, WDDX, XML, and XSL module for PHP

On OMV 3.0 PHP works out of the box.
Did I miss something during installation of latest stable OMV 4.1.22?

I found a solution to problem:

in command line

nano /etc/nginx/sites-available/zzz-omv-nginx

rewrite a line from something like this:
set $socket "unix:/var/run/fpm-4822da3c-c441-43fa-880a-30171aa10b58.sock";
to:
set $socket "unix:/var/run/php/php7.0-fpm.sock";

and then
service nginx restart

and php works!

Unfortunatelly OMV keep switching back to wrong setting.
How to make correct settings to stay for good?