Are you running any firewall software on the webserver? iptables is activated by default. You may want to shut it off just for testing purposes.
Also, are you running TCP wrappers, in other words, do you have entries in your /etc/hosts.allow and /etc/hosts.deny file? Try commenting out any you may have and try testing.
One more thing do you have access controls for your website in your httpd.conf file, limiting access to only to the 192.168.x.x network?