There is nothing, as far as I can understand and test, wrong with the versions of COPS, PHP and calibre.
Did you test with and without the password option working in .htaccess?
And did you (of course you did) restart/reboot your qnap?
And COPS works as expected if you do not use (click on) the custom columns?
The OPDS feed of COPS (
http://[MYIP]/COPS/feed.php ) works as far as I understand COPS through PHP and not apache.
If you use an OPDS enabled ebook reader on iOS that would fix your problem, but not if you want to use your Kobo webbrowser with COPS.
What I can advise is:
- make a new installation of COPS in a new directory on your Qnap (../cops2)
- start with copying config_default.php to config_local.php
- only add one calibre (test) database to config_local.php
> test if this works
- add
$config['cops_calibre_custom_column'] = array ("demo");
> test if this works
- etc. if it works just keep adding line after line. If not
(maybe there is weird typo somewhere that neither of us sees .....)
The line
$config['cops_subtitle_default'] = "Epub et PDF"; should have no effect in Apache.