If you're using the "port forwarding" rule of a NAT-router to show the site, other machines on the network may not be able to see it.
This is because the router refuses to pass the same connection through the NAT process twice (once for SNAT, again for DNAT). So technically this is a router limitation.
There's no reason in principle why the same connection can't be SNAT'd and DNAT'd, some routers do have this feature. See the documentation for more info.
Mark