Fix problem with Magento 2.3.3.p2 / Theme Magento 2 Luma / php 7.2 Apache FPM

Hi ,
i have problem with Magento 2.3.3.p2 / Theme Magento 2 Luma / php 7.2 Apache FPM now in Production Mode .
The site is crashing all the time. I currently have no errors in system.log and debug.log. I would like to understand if it is a server resource problem and possibly which parameters I have to increase from my provider.
Now the site is in production mode with warnish cache because in default mode I could no longer use it.
Reindex is too slow
Errors:
504 Gateway Time-out
err_connection_aborted

bash-4.3$ /opt/plesk/php/7.2/bin/php -i | grep max_execution_time
max_execution_time => 0 => 0
bash-4.3$ /opt/plesk/php/7.2/bin/php -i | grep limit
memory_limit => 769M => 769M
Total Links => 0/unlimited
ldap.max_links => Unlimited => Unlimited
mysqli.max_links => Unlimited => Unlimited
mysqli.max_persistent => Unlimited => Unlimited
odbc.max_links => Unlimited => Unlimited
odbc.max_persistent => Unlimited => Unlimited
pcre.backtrack_limit => 1000000 => 1000000
pcre.recursion_limit => 100000 => 100000
pgsql.max_links => Unlimited => Unlimited
pgsql.max_persistent => Unlimited => Unlimited
session.cache_limiter => nocache => nocache
soap.wsdl_cache_limit => 5 => 5