Nice, great it works now for most people.
Oh boy, thanks for the update but this is way beyond the average users head never mind the fact that most users don't even have access to there servers at this level and trying to get a host to make these changes who don't generally want to get involved is going to be a nightmare for allot of people, is there not easier way to get Virtuemart working again without the need for technical server configurations?
You seem to misunderstand the problem. There is something in your setup, which prevents that your server gives the correct client IP. This means that there is a special setup, which usually also includes these technical details.
What I did now is to use the defacto convention, but as I said before it is NOT a rule, and NOT a real convention. This is the reason it helps most users, but not anyone. So your hoster must give you this information.
But as I wrote before, you can try to find yourself. It should even work with the joomla sysinfo. Go here /administrator/index.php?option=com_admin&view=sysinfo to the tab PHP Information, then search in the Apache Environment variables for your own IP. There you can see also the problem, you will have something like
But remote address should be the IP of the client. Actually yours. So in your case, you need to find a variable there, with an IP, which is yours (check your router, to get your IP). So if you find then the variable with your IP, just enter it in the config field and it should work, then.