Hi,

thanks for your suggestion. Tried this well without success. It seems, I did not describe the issue properly, though.
Just found a post (which you replied) describing a very similar situation: http://www.ruby-forum.com/topic/860524.
The problem in both cases is IP sharing on the backend/upstream side and that the upstream hostname cannot be assigned and forwarded to the backend dynamically by nginx. Did this change in the meantime?

Thanks
fatzopilot