My requests get cut off on the host

Part of my <stack> app takes a while: <describe it>. On <host> it gets
cut off with <the error or behaviour you see>.

Explain:
- Which timeouts are in play here: the web server, the language runtime,
  a proxy, the browser.
- Which of them I can raise on this host, and which I can't.
- Whether raising them is even the right fix.
- How to restructure the work so it finishes in the background and the
  page checks back, using only what this host supports.

Recommend one approach.