link to index.html on iPhone

I have been trying to get my site to work on iPhone (3G) for awhile now. It works on Android, tablets and iPads but not iPhones. I finally got it to where it was somewhat usable. I then tried to modify the “this is embarrassing” message in the 404.php file and now the site does not work on mobile devices. It appears the site is trying to link to an index.html file that does not exist. The site is https://www.parkilasports.com. Any help is appreciated, thanks!