I'm having problems reading the daydream comics using Firefox on Arch Linux. It works when I use Midori on the same computer or using Firefox on OSX.
The problem is that even though the webpages are displayed, the actual comic image does not load (firefox gets a HTTP 403 Error).
Here is a screenshot:
The Problem persists, no matter which (daydream) comic I'm viewing.
Also, I made sure that I am logged in.
Where I work, we once had a similar problem. In our case it was the user-agent string which triggered our server's bot protection.