We’re using mod_rpaf and trying to use it for SSL offloading so we can cache all HTTPS requests with Varnish. This has worked well in testing, but on production, we’re seeing intermittent port errors. So making 1’000 requests to the same URL over HTTP, we get several hundred requests showing in the apache logs as port 443.
This causes all sorts of unexpected side effects. Particularly with mod_pagespeed which serves 404 when the port has been set incorrectly. Nightmare.
Bottom line, we’ve take this out of our architecture until we can find a solution. The hardest part is that we can’t replicate the issue on staging. I’ve opened an issue.