hacker3000
PHP function fsockopen is not available. Maybe your hosting provider disabled it for some reason?
cziehr
It is absolutly no problem to use DokuWiki without an internet connection. It is a bit more work to update plugins and the core of the wiki, because the updater doesn‘t work, but this is the only real constraint which I found. I‘m using a DokuWiki without an internet connection since 2014.
martinr
One other minor niggle when not connected: help pages are not available. You'll probably end up collecting a bunch of them from the main site and installing them elsewhere. You do at least get the basic syntax page included automatically.