@andstatus Different webservers and configs.
Quitter.se runs Apache with mod_php - that does _not_ use CGI.
LoadAverage.org runs nginx v1.6.2, maybe he has even applied the config fix?
I don't know about @vinilox@status.vinilox.eu but I would guess he runs a similar config to #

The nodes where "411 Length required" come up run some form of fastcgi (php5-fpm uses the fastcgi interprocess protocol) _without_ special configurations (I call bypassing error messages special). These are at least quitter.es, quitter.no and social.umeahackerspace.se for example. My nodes run lighttpd and php5-fpm, quitter.no run Apache.

Different webservers behave differently, despite there being a specification, and so far the only one which has shown to work without throwing an error is an nginx configuration with a special, non-default setting which @knuthollund could _not_ replicate using standard Debian (version "stable") packages.