I have logged into contribs.org from a Linux distro that I booted from a USB stick,
http://slax.linux-live.org/ In the one window I am online to the sme server manager and in the other I'm online to contribs.org
During the years I have never experienced problems to log on the server-manager panel from any Linux distribution.
I do agree that the problem is likely to be somewhere else, like the dns resolver setup of the Mandrake or a firewall problem.
To clear out a firewallproblem on the Mandrake PC, I think you can only run this command from shell: "iptables -F", and then "iptables -L" to check that it is open.
Then to eleminate a dns resolving problem, you can just logon to the server manager like this:
http://10.0.0.2/server-manageror this:
https://10.0.0.2/server-managerI allways use the local ip adress when I log in from diverse more or less experimental Linux distributions, just to avoid this typical dns problem on the lan.
Please report back if it did work or if it did not work.
Best reg Arne.