I had a strange problem with Varnish, when users used form for longer period, like they inputed data and then submitted if it was 120 seconds or more, edit page would just refresh and nothing would be submitted. So I played with TTLs https://www.linode.com/docs/websites/varnish/getting-started-with-varni…, then with pipe_timeout
http://frank.be/pipe_timeout-most-under-documented-varnish-parameter/ but this all didnt help, but I did notice that set beresp.ttl in vcl_fetch would change behaviour of the form and would make it unsubmittable. I was going with some idea that varnish refreshes page every 120 seconds so if you wait longer, page gets refreshed and form is outdated. But it wasnt that also, or at least I couldn't get it work properly as there is also a default varnish_TTL in /etc/sysconfig/varnish file, not in default.vcl and I am not sure how they all play out in the end. So what I did is I made this. Remove POST from caching, in a way to just add in sub vcl_recv
if ( req.request == "POST") { return (pass); }and that made it work. Varnish was no longer messing up form submits. I just tested it out, even after 30 minutes I can submit a complex node form. It WORKS!!!