Are you getting a weird error from varnish that you’re having trouble working out? Is it cryptically saying that there’s an issue with your host definition in your VCL?

Expected ID got ';'
 (program line 165), at
 ('input' Line 20 Pos 30)
 .first_byte_timeout = 120;
 -----------------------------#

You need to add a time unit to your timeout definitions — ‘s’ for seconds, ‘m’ for minutes.  Stupid cryptic error is dumbly cryptic. Grrr.
https://varnish-cache.org/lists/pipermail/varnish-bugs/2011-August/003983.html