Oy vey. So I typed in the IP, directly, didn't work.
I added the host name thing according to the directions. I was reading and typing it off my phone, which like I said only got the site when I turned wifi off on the phone.
I reset the cache from the navigator thing like it said. Didn't work.
I looked in my history like Jayne suggested, but I had cleared it this morning troubleshooting this.
I googled "safari can't find server" and I got thishttps://discussions.apple.com/message/25093236#25093236
The part that worked for me wasPower off the router. Wait awhile. Power it back on. Wait until all the lights are lit up properly.
Poet could it be your router too?