Server with Perfect setup, not functioning in Datacenter

[Hans]

I have setup my new server according Falko’s “Perfect setup” for Debian Sarge.
I have tested this server at home and everything was functioning fine!

After changing the network-settings like DNS-servers, IPadresses, subnetmask etc, I have brought the server to a Datacenter a problem appears.

I have connecion on ports 21 (FTP) & 22 (SSH) but…no connection through port 80 (http).
When I ping to the server there is no data loss.

What could be wrong?

Please try to help me.