The URL http://www.faqforge.com/linux/controlpanels/ispconfig3/how-to-update-ispconfig-3/ resonds with " Firefox can't find the file at http://www.faqforge.com/linux/controlpanels/ispconfig3/how-to-update-ispconfig-3/." It appears to have gone missing at around 12:45 BST today See link Ispconfig update instructions http://www.ispconfig.org/ispconfig-3/documentation/
The page http://www.faqforge.com/linux/controlpanels/ispconfig3/how-to-update-ispconfig-3/ open fine from here and there is nothing missing on the page and the link on the ispconfig documentation page works too.