Problems with 404 pages and .htaccess files
Create a .htaccess and that’s it
ErrorDocument 404 /missing.html
On the homepage, you need to make sure your host supports .htaccess..
To modify the conf file, you need to restart apache..
It has nothing to do with UrlRewrite, it mainly depends on whether it supports .htaccess
Add a sentence if you support:
ErrorDocument 404 /my404page.html