Sorry for the inconvenience. Known Navigation header breakage, its being "rebuilt."
There may be other unforeseen breakage primarily in the handbook portion of the wiki.
The Table Of Contents section of each "PC-BSD® Users Handbook" page may be the best workaround.
Category talk:Pages with broken file links
Ok. As mentioned on the parent page, This category seems to list pages that contain the old method of including images. The strange part is that Network configuration and Flat html are the only two pages that have yet been listed here. The individual pages that are aggregated by Flat html, ought to be listed here as well. The apparent disparity seems to be caused by a sort of cache which is not immediately updated.