Just evaluating / getting used to Virtualmin. Using Apache on non-standard port (in my case to use Varnish), this thread is relevant https://www.virtualmin.com/node/19887
There are problems: 1. When Virtual host is configured for non-standard port, Server Configuration > Website Options returns the error "Website options cannot be edited, as no Apache virtual host for mysite.com port 80 was found!" 2. Every virtual host must be individually edited to change port. Since apache is no longer listening on 80, it would useful for this to be automated. It would also be useful to be able to change other settings globally e.g. change php handler, and override / bulk write the local php.ini.