website denites access if not on local subnet

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http://forums.fedoraforum.org – I have a website running, and locally, I can access it with no problems at all. I can access it from any computer on the same subnet as the web server. But if I try to access the site from outside, I get an error (generated by the server), that I am "forbidden" to access the site. (I believe it's a 403 error, but can't recall at the moment). Even if I VPN into the same subnet, I cannot access the site. I've checked log files, but don't see anything unusual, and checked the httpd.conf, and as far as I can tell, it's set to "Allow From All"... Any ideas? (HowTos)