I've been using Caddy for years as a reverse proxy in front of other services, but recently wanted to use it to directly route traffic to PHP-FPM. Caddy has a specialized reverse proxy directive for PHP-FPM, php_fastcgi, which seemed like it would do the trick, but I found that no traffic was ever getting routed to my FPM pool.

I've been using Caddy as a front-end reverse proxy for several years now, on the advice of Marco Pivetta. Somewhere along the line version 2 was released, and I updated at some point, but evidently didn't quite understand some of its configuration options, particularly around HSTS support and providing your proxied application information about how the client tried to connect.