Public page cached

Problem/Motivation

I'm trying to set a public page on my website to not be cached. It shows the most recent pictures from a webcam. At present, logged-in users see the most recent pictures, but the general public sees older pictures that were the most recent whenever I last logged in and visited the page.

I know that it's the website sending out cached pages and not the browser because I used the dev mode to do 'empty cache and hard reload', and nothing changed, it shows pictures from 5h ago. However if I change the number at the end of the url to one that I haven't used before then it shows me the new images.

Steps to reproduce

The page that I want to be updated with each visit is /campics/laurel_ridge/12
where the number on the end can be anything up to a hidden limit, it specifies the number of pictures to show.

In the module configuration I have
Exclude cache for page variation with query parameters
/campics/laurel_ridge
and
Paths to exclude
/campics/*
/campics/laurel_ridge/*

Under admin/config/development/performance I set the regular cache age to 15 minutes.

Did I misunderstand the instructions? Is this module unable to do anything for my cam pages because I created them with a custom module?

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes