iPad and calibreweb

I have a Calibre server set up in ubuntu and calibreweb in docker. I'm using a reverse proxy so I can access calibre via calibreweb.mydomian.com.

I can access it fine, see all the books on any device using the above address. (I have a mix but mostly comics right now)

However whenever I try to read a comic (but any book as well) nothing happens. I can select to download but it never downloads. I can't read in the browser.

I've been trying on my iPad but it does the same on my desktop Mac.

Did I miss something in set-up?