Apache replaces ip-address with (local) hostname
I am having a problem with my Apache server at home. Everything is working fine when I access the webpages from the intranet. The problem occurs when trying to access the pages from the internet. I don't have a domainname, so I access it directly via the IP number. When I access for instance Horde or Gallery from the internet, I get (after the login) redirected to servername.mylocaldomain.intra, which is obviously not known on the internet. I assume that I somehow configured Apache in the wrong way (although for instance phpgroupware is working fine). How do I stop Apache from replacing the IP number with the local computer name?