Maximum FCGI execution time
By default, Virtualmin sets the maximum execution time for FastCGI processes to match the execution time of PHP scripts, as determined by the domain's php.ini file. This ensures that PHP applications will not run for longer than they are supposed to.

However, you can disable this behaviour by selecting Don't set in this configuration field. Or you can specify your own timeout for fastCGI scripts by selecting Time in seconds and entering a number.

This is implemented by setting the Apache IPCCommTimeout directive, or the equivalent in Nginx.