I won't hound you on this one, but you have to read to learn
Other than that, theres a couple things regarding your problem that I would like to clearify.
I am going to go under the assumption you are on the same subnet, but I have to ask, is this computer on the same subnet as the computers trying to access it ?
When you tested with the sample index.php, what did you type in the browser URL to view it ?
Is there by chance some firewall rules set that could be blocking access from other workstations. I asked this cause I know what that Fedora installation defaults to, and this is something I am suspecting.
For the sake of trying it, look at what rules are presently there by typing :
If there is results, and If you see something there that you suspect is causing the problem or if you just want to do this as part of troubleshooting, you can type :
This will flush the firewall rules on this box that were set.
And see if you can get on. If you can then there was a firewall rule blocking your access obviously.
Get back to me with the original two answers if the firewall is not the problem.