Currently, the homepage of my Joomla is /index.php...

But the one that appears when you don't type it in (just leave it at the /) is /index.html.

How do I get /index.php to replace /index.html?

Delete the index.html. Assuming it's the standard Zymic index, and not put there by Joomla.

swordz

Worked, thank you.